Tipping is more than just a custom; there really is a culture to it. If you're tipping only because you know the server makes less than minimum wage from the restaurant (or that greedy restaurant owners are completely to blame for this injustice), I think you may be misunderstanding an aspect of this culture.

Working in a restaurant is as hard a retail job as there is, and working as a server is often the hardest job in the restaurant. Being a truly good server requires a rare mix of people skills, math skills, memory, and a thick skin. So why do people choose to take the hardest job there is in the whole restaurant, when it pays less than all the other jobs?

Most servers end up getting paid better than the people doing other jobs in the restaurant. In most restaurants, servers make more than minimum wage. At the end of their shifts, most servers in turn tip-out the front-of-the-house employees, such as hosts and bussers, who often do only make minimum wage.

A truly excellent server may be the highest-paid employee for an entire shift -- that certainly includes the manager and anyone else on salary, and it may even include the owner, when you add in labor and upkeep costs.

In order to make all that money, however, this server has to work at all the times that everyone else is out having fun -- Friday night, Saturday night, Sunday morning. This server must put up with drunks, picky eaters and other narcissists, as well as seating errors and kitchen mistakes, all with a smile, for six or eight or ten hours straight. This server, who earns more than anyone else on the shift, is working harder than anyone else on the shift.

This is the other aspect that I wanted to address. Tipping culture is what gives that excellent server the opportunity to earn a better wage, more appropriate to the effort and expertise they devote to the job.

I'm sure this all sounds very capitalist, because it is. This may not be the most capitalism-friendly forum, I know, but I'm not trying to make any larger argument here.

I'm just saying that to me, it seems like this should be a "don't hate the players" (owners, managers, servers, rich/drunk people who like to leave big tips) "hate the game" (tipping culture). And even if you do hate tipping culture, it couldn't hurt to consider how it works for the people who don't hate it.