When you talk about not tipping for "moral reasons," imagine in your head that you are at a restaurant in America explaining to your server why you've opted not to tip them. Imagine their eyes glazing over as you explain why you're not participating in the "broken" system. Imagine the thoughts running through their head: "I guess my kid has to eat PB&J all week." "I can't even get a beer after this double-shift." "I would strangle your dumb ass, but then I'd be fired from my only meager source of income." Even if you think it's a bad system, you're not making a difference by not tipping. You're just screwing up someone's plans.
While I'm generally in favor of changing the tipping system, another poster has reminded me of a big knock against it: companies suck ass. When I worked as a server, we had the usual tip jar plus an option for tips on credit/debit payments. Cash tips were doled out at the end of the night, credit tips were distributed in cash at the end of each pay period along with standard pay checks. Very suddenly, credit card tips (which usually came out to around $200) started decreasing dramatically for no apparent reason. A couple of weeks later, a fellow server was promoted to a manager position. He wasn't filling a vacancy; the position was created. As he was a fellow server, he let me in on a piece of information: instead of altering the budget or decreasing payouts to the ownership, they had decided to pay the difference between his server salary and his manager salary out of the whole team's credit card tips. Who would know? This is why I ALWAYS tip cash rather than on a card if I happen to have some on-hand.
This is all to say that employers frequently treat their employers like crap and want to maximize profits. Capitalism, baby! I understand the impulse to want to keep a large portion of your income out of their reach to prevent malfeasance, but that depends on literally everyone else playing ball. It should still change, but it obviously needs to be done in ways that hold employers accountable to their employees.