As bad as salaries have gotten over the years, I think we make more than taxi drivers and waiters. Well, at least most taxi drivers and waiters.
Plus those are not salaried positions, tips are a large percentage to certain hourly-compensated workers in most "service" jobs.

Thirdly, even if it was customary to tips flight crews I wouldn't start lighting cigars with $100 bills since most people on average don't tip well. I've waited for a few years and I'd say in average tips were 10%-12%, but then again I wasn't a very good waiter. Apparently bad people skills and being a pilot go hand in hand.