It seems there's a lot of discussion about getting rid of tipping, but I don't know how much has changed in this regard.

Nothing has changed, and it never will, as it concerns poor and "therefore" "deserving" people. Americans' talk is cheap.

The system seems ridiculously unfair, and that extra expense in a country where everything is already so expensive really makes a difference.

Agreed. So when you go to a restaurant and you have a maximum amount you can spend, divide the amount of money you have by (100% + local sales tax), then divide by (100% + the menu price), and subtract any surcharges added by the restaurant (assume $5.00 if you cannot look it up), often masquerading as a tip. I know it's a lot of math, but you have a computer in your pocket. You'll manage.

In my view, the US is a fractal scam. At every level, everything is an attempt to extract money from ill-informed "suckers", from the running of the government, to the prices of supermarket groceries, to the tipping culture at restaurants, to even finding a place to put your car [1]. Every single thing is someone's grift. In order to function in America, you need to be willing to be suckered to some extent. There's no way around it. Unfairness is baked into every transaction, and increasingly more social interactions.

Everything in America is ridiculously unfair. We wear this on our sleeves, and for many Americans this fact defines their personality. Unfortunately, you will have to deal with it in the short term at least.

Now if you would like to be the one to lead the charge against the tipping culture and the foisting of responsibility for servers' compensation onto the customer, then be my guest. Refuse to tip and make a big scene about it. Make plans for how to take the inertia of your big struggle and turn it into a mass movement. I would thrilled to join you. However, I somehow doubt that you're ready to go that far; none of the customers who stiffed me ever went on to start anti-tipping movements.

So will AITA if I don't tip?

Yes. You are expected by all members of the public here to tip. That is our culture, something we're proud of for some reason, and our expectation. For some servers, tips are the primary source of income at work.

Is it really my personal responsibility to make sure my server is paid enough?

No, it is the responsibility of the employer. However, when no employer takes their responsibility and you sit yourself down at a restaurant, the logical conclusion is that either you pay that part of the server's wages, or they get stiffed. You know that this is the conclusion. (Or if not, now you do.)

If you want to participate in our unique restaurant scam, you gotta accept that you're going to get suckered into paying the server's wages. Otherwise, don't go to restaurants. When you go to a restaurant, you waste the employees' finite time on this planet doing tedious, physically and mentally demanding bullshit that no sane person would choose to engage with, if not faced with the threats of homelessness and starvation. [2] At least make it worth their while.

Sorry if I come off as having a chip on my shoulder, but that's only because I totally do. So many customers used to concern-troll me as a pizza delivery person and give me shit like "sorry, couldn't afford to tip, they should really pay you more." Yeah, they should, but you absolutely could have tipped; all you had to do was order one less topping. I'd love to see some actual solidarity with food service employees, but that would require challenging deep-rooted assumptions about our culture and we're too shit-for-brains to do that. Americans are so compassionate and empathetic until the moment they actually have to lift a finger.

So when someone brings up "unfairness" or "it's X's responsibility to pay the workers" in response to tipping, I just kinda die a little inside from all the times those sentiments have been used against me and my colleagues.

[1] And don't even get me started on the process of buying a car, or how the public was scammed into accepting a car-centric infrastructure.

[2] This is really a special case of the logic behind the antiwork movement: nobody actually wants to go to work. We only go to work under the threats of starvation and homelessness imposed by capitalism.