When the market arranges itself to pay servers 10-15% less than what the prevailing rate would be without tipping, the market is saying that servers are entitled to tips just for doing their job.
It is indeed true that servers expect a 15% tip simply in exchange for competently performing their job. So do their employers, and so do the majority of restaurant patrons.
I'm very unlikely to ever end up eating in a restaurant with you. I mostly do not care whether you tip or not. But the parallels between this thread and threads about software pricing are spooky: it's as if the part of the brain that enables most people to understand pointers-to-pointers and function pointers somehow cancels out some of the part of the brain that enables people to intuit how markets work.
Suffice it to say I am geeking out over this issue, not moralizing about it. Although: there's a moral component, and as a message board nerd, I'll pitch a little fit if we pretend that there isn't one. :)