You don't have to agree with it for it to be happening. Though, understanding that side of the argument can help solve the problem for both sides of the equation.
The moral way to improve your pay is to find a way to make your labor worth more to the employer.
For a restaurant worker, that could be things like finding ways to boost sales, reduce wastage, find less expensive vendors, improve efficiency, etc. It's highly unlikely that any restaurant has successfully optimized all aspects of their operations.
What, for free? He isn't being paid to do that.
If you choose to do as little as possible, it does make for a tough negotiating position when asking for more pay.
When I've gone into my boss's office and negotiated for more pay, I'd come in prepared to show how I'd already demonstrated higher value to the company. Sometimes I walked out with a raise, and other times I failed and started looking for another boss who did value what I could do for him.
On the other hand, I knew coworkers who were thieves and justified it with their notions of entitlement. I didn't exactly feel inclined to trust them, either, and trust is a basic element of friendship.
So I guess we all get to make our choices and accept the consequences.
I.e., the old crabs in a bucket story. http://en.wikipedia.org/wiki/Crab_mentality
From a static point of view where the job situtation will never change it doesn't make sense to put in an effort that exceeds the compensation but that 'solution' is certainly non-optimal from dynamic point of view where the employment contract gets continually revised over time resulting in raises, promotions or perhaps shifting to a new employer where your experience and skills result in a better employment situation.