I worked in kitchens for years, mostly school cafeterias, but for a while I was a short order cook in a diner and I never got a share of the tips. I was paid about $1 more an hour than minimum wage and the waitresses were paid $.50 less per hour (because at the time I do believe the waitress minimum wage was less due to tips). So basically a $2 tip an hour meant the waitstaff made more than me.
I didn't like it so you know what I did? I stop working in those jobs.
I agree dealing with customers sucks ass, but I've come to embrace the Australian notion of no tipping unless it's exemplary service. There's a base level of service they're paid to produce and if that's all they do, they don't deserve a tip.
There are lots of other customer service focused jobs (my current job of car salesman for instance) that the notion of tipping never even pops into people's heads, so why do we think of waitstaff and bellhops differently? Again, I'm fine with tipping for exemplary service but if all you're doing is your basic job of taking my order and bringing it to me then no, that's not worth an special recompense and why should it?