That's still someone's rent and food money you are withholding from them by not tipping. It's a fucked up system, but they wont be compensated by their boss when you stiff them. So not giving them that tip could be the difference between choosing to pay for rent or groceries this week.
Refusing to tip does nothing but harm workers and allowing the owners to continue to profit. The whole system needs to be reworked from the top down. There is no reason that a restaurant can't just pay their workers a fair wage. They could also just automatically give the staff X% of total sales, but then that starts to sound like a co-op, and then people might start to ask themselves what the owner actually does for the restaurant.