re: Is tipping primarily a learned behavior?

Yes, and I have a few theories why people do not leave tips.

1.) People tend to judge the food when leaving a tip. I have eaten with people and when they feel like they got a poor value in the food so they left a smaller or no tip. Obviously that has little to do the server but that is just how people feel sometimes.

2.) Gratuity, this is no big deal on huge parties but a lot of places now do it on a 6 top. I have seen historically good tipper become poor tippers due to this. I don't know if it is because they feel that they paid gratuity in the pass for sub par service so it all evens out, or because now they just expect it on their bill and literally don't think about tipping.

3.) The cost of food is going up and for some reason the percentage that is normal to tip is going up. For a lot of people it is just a matter of if they can afford to do so. For example, me and my wife went to olive garden with two kids under 6. My bill was $57.00, we all drank tea and basically ate a tv dinner. The server never had to to refill drinks or do anything beyond taking our order and bring the food. I tipped $9.00, but after I left I thought, wow, nine bucks in 30 minutes for 3 minutes of work and bad. And $66.00 is a lot for basically 3 tv dinners