You sound like a very nice person and I hope we get you on our next vacation! Keep up the attitude you have going on here and YOU will be one of those full time servers that make that $76,000+ a year! If you go in and do your job well you get rewarded! Most people do tip 20% so a lot has to do with the server and how they treat their tables. Sounds like you know exactly what to do to make the best tip!
If you could work at any WDW restaurant which one would you choose? I am a little surprised that the ones bringing in the $76,000+ are the buffet servers. You'd think their averages would be the lowest judging from peoples view on buffet tipping. Personally I think they do just as much. Refilling the drinks and removing dirty dishes are the two things most important to me.