politics

No that's not it. They hate Turks, because they abused them for cheap labor (and still do) and racialized them to organize the exploitation materially, to justify it ideologically and to compartmentalize it psychologically. Like any racialized group, they are seen as less than human.

With the economic restoration after the war, the demand for labor was high, driving up wages and cutting into profits. Starting 1961, German capital brought Turkish people over to do all the dirty, badly paid work. Six years earlier, they had started with Italians, other nationalities should follow until today. They denied them the rights white Germans would get and kept the threat of deportation dangling over their head to keep them in line. They made a law to prevent "communist infiltration" to ensure any of the "guest workers" who showed any sign of organization or class consciousness, could be immediately deported. It worked, unemployment rose, increasing the reserve army of labor, driving down wages and stabilizing profits.

It's a classic contradiction: capitalism needs cheap, overexploited, racialized labor, so they need to create racist ideology that justifies the cruelty and demarcates who to overexploit, but that ideology threatens the system of "guest workers" for racist reasons. The temporary "solution", as for most contradictions, is to move the contradiction elsewhere for others to suffer the consequences. In this case by de-industrializing and moving production offshore to labor markets where wages are kept low by force. Until that stops being enough (to offset the tendency of profits to fall) and the colonial methods turn inwards: fascism. That's what's happening now.