You're wrong.
It may work that way at McDonald's, but when the choice of entree, an extra app or dessert, or a couple of extra cocktails can easily add $100 to the bill, I will hire the most ambitious waitstaff I can.
I worked for about 10 total years as a waitress.
There were weeks when I’d take home gobs of money.
Why? I went the extra mile, knew my stuff, was pleasant at all times.
I worked at very high end restaurants and medium end restaurants.
As a tipper I tip 20 for regular good service 25 for exceptional service and 15 for average service. ANd if I tip that 25 I let the person know what he or she did that made me give that extra because it may help them get that extra from others.