A tipping system is superior to a wage system in many regards. It often results in higher wages for the employees. A store owner will obviously work hard to make sure his employees get as little as possible without damaging work flow; customers paying employees directly are typically as frugal.
It also rewards diligent workers well, and rewards them more immediately. You don't have to work hard for an entire year in the hopes that maybe at the end of it there will be a salary increase; the reward for good work is provided right then and there. Good waiters get better tips. If you decide to slouch off the next day, tips will likely go down. Work hard the day after that, tips will likely go back up again. Immediate, direct incentive to work hard right now, and not just a month before review and hope the manager forgets the previous 11 months.
Not to suggest a salary system doesn't have it's benefits, too. A hybrid system, as we have here in the US for waiters and a few other workers, strikes me as the best option available. Some salary as a baseline, and tips to incentive hard work and increase overall worker pay beyond what they'd get if they were salaried only. I am not only against getting rid of the tipping system, I am for implementing it in more places than we already have it.