Service charges can be adequately split between all employees, whereas an increase to the price of a dish will typically just result in a larger tip to the server that is not split to other parts of the restaurant. Tipping in general relies on a lot of "good actors," between customers determining what they really want to pay for a meal to servers correctly reporting what they receive and tipping out accordingly. A better model is to tell you directly what you're going to pay, and you shouldn't feel compelled to pay any more than that amount.