Many such cases. I forget the essays, but I'm pretty sure there's a lot of Marxist literature that talks about Unionism not being the end-all of working class struggle. Without Marxism as a foundation of unions, they are often used against the working class as a whole.

Vladimir Lenin’s “Left-Wing” Communism: an Infantile Disorder

Should Revolutionaries Work in Reactionary Trade Unions?

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In its work, the Party relies directly on the trade unions, which, according to the data of the last congress (April 1920), now have a membership of over four million and are formally non-Party. Actually, all the directing bodies of the vast majority of the unions, and primarily, of course, of the all-Russia general trade union centre or bureau (the All-Russia Central Council of Trade Unions), are made up of Communists and carry out all the directives of the Party. Thus, on the whole, we have a formally non-communist, flexible and relatively wide and very powerful proletarian apparatus, by means of which the Party is closely linked up with the class and the masses, and by means of which, under the leadership of the Party, the class dictatorship is exercised. Without close contacts with the trade unions, and without their energetic support and devoted efforts, not only in economic, but also in military affairs, it would of course have been impossible for us to govern the country and to maintain the dictatorship for two and a half months, let alone two and a half years. In practice, these very close contacts naturally call for highly complex and diversified work in the form of propaganda, agitation, timely and frequent conferences, not only with the leading trade union workers, but with influential trade union workers generally; they call for a determined struggle against the Mensheviks, who still have a certain though very small following to whom they teach all kinds of counter-revolutionary machinations, ranging from an ideological defence of (bourgeois) democracy and the preaching that the trade unions should be “independent” (independent of proletarian state power!) to sabotage of proletarian discipline, etc., etc.

We consider that contacts with the “masses” through the trade unions are not enough. In the course of our revolution, practical activities have given rise to such institutions as non-Party workers’ and peasants’ conferences, and we strive by every means to support, develop and extend this institution in order to be able to observe the temper of the masses, come closer to them, meet their requirements, promote the best among them to state posts, etc. Under a recent decree on the transformation of the People’s Commissariat of State Control into the Workers’ and Peasants’ Inspection, non-Party conferences of this kind have been empowered to select members of the State Control to carry out various kinds of investigations, etc.

Then, of course, all the work of the Party is carried on through the Soviets, which embrace the working masses irrespective of occupation.

Including baristas lmao

The district congresses of Soviets are democratic institutions, the like of which even the best of the democratic republics of the bourgeois world have never known; through these congresses (whose proceedings the Party endeavours to follow with the closest attention), as well as by continually appointing class-conscious workers to various posts in the rural districts, the proletariat exercises its role of leader of the peasantry, gives effect to the dictatorship of the urban proletariat wages a systematic struggle against the rich, bourgeois, exploiting and profiteering peasantry, etc.

Such is the general mechanism of the proletarian state power viewed “from above”, from the standpoint of the practical implementation of the dictatorship. We hope that the reader will understand why the Russian Bolshevik who has known this mechanism for twenty-five years and has seen it develop out of small, illegal and underground circles, cannot help regarding all this talk about “from above” or “from below”, about the dictatorship of leaders or the dictatorship of the masses, etc., as ridiculous and childish nonsense, something like discussing whether a man’s left leg or right arm is of greater use to him.

We cannot but regard as equally ridiculous and childish nonsense the pompous, very learned, and frightfully revolutionary disquisitions of the German Lefts to the effect that Communists cannot and should not work in reactionary trade unions, that it is permissible to turn down such work, that it is necessary to withdraw from the trade unions and create a brand-new and immaculate “Workers’ Union” invented by very pleasant (and, probably, for the most part very youthful) Communists, etc., etc.

Capitalism inevitably leaves socialism the legacy, on the one hand, of the old trade and craft distinctions among the workers, distinctions evolved in the course of centuries; on the other hand, trade unions, which only very slowly, in the course of years and years, can and will develop into broader industrial unions with less of the craft union about them (embracing entire industries, and not only crafts, trades and occupations), and later proceed, through these industrial unions, to eliminate the division of labour among people, to educate and school people, give them all-round development and an all-round training, so that they are able to do everything. Communism is advancing and must advance towards that goal, and will reach it, but only after very many years. To attempt in practice, today, to anticipate this future result of a fully developed, fully stabilised and constituted, fully comprehensive and mature communism would be like trying to teach higher mathematics to a child of four.

We can (and must) begin to build socialism, not with abstract human material, or with human material specially prepared by us, but with the human material bequeathed to us by capitalism. True, that is no easy matter, but no other approach to this task is serious enough to warrant discussion.

The trade unions were a tremendous step forward for the working class in the early days of capitalist development, inasmuch as they marked a transition from the workers’ disunity and helplessness to the rudiments of class organisation. When the revolutionary party of the proletariat, the highest form of proletarian class organisation, began to take shape (and the Party will not merit the name until it learns to weld the leaders into one indivisible whole with the class and the masses) the trade unions inevitably began to reveal certain reactionary features, a certain craft narrow-mindedness, a certain tendency to be non-political, a certain inertness, etc. However, the development of the proletariat did not, and could not, proceed anywhere in the world otherwise than through the trade unions, through reciprocal action between them and the party of the working class. The proletariat’s conquest of political power is a gigantic step forward for the proletariat as a class, and the Party must more than ever and in a new way, not only in the old, educate and guide the trade unions, at the same time bearing in mind that they are and will long remain an indispensable “school of communism” and a preparatory school that trains proletarians to exercise their dictatorship, an indispensable organisation of the workers for the gradual transfer of the management of the whole economic life of the country to the working class (and not to the separate trades), and later to all the working people.

In the sense mentioned above, a certain “reactionism” in the trade unions is inevitable under the dictatorship of the proletariat. Not to understand this means a complete failure to understand the fundamental conditions of the transition from capitalism to socialism.

Looking at you, Polandia.

It would be egregious folly to fear this “reactionism” or to try to evade or leap over it, for it would mean fearing that function of the proletarian vanguard which consists in training, educating, enlightening and drawing into the new life the most backward strata and masses of the working class and the peasantry. On the other hand, it would be a still graver error to postpone the achievement of the dictatorship of the proletariat until a time when there will not be a single worker with a narrow-minded craft outlook, or with craft and craft-union prejudices. The art of politics (and the Communist’s correct understanding of his tasks) consists in correctly gauging the conditions and the moment when the vanguard of the proletariat can successfully assume power, when it is able—during and after the seizure of power—to win adequate support from sufficiently broad strata of the working class and of the non-proletarian working masses, and when it is able thereafter to maintain, consolidate and extend its rule by educating, training and attracting ever broader masses of the working people.