PDT 2/2 : Why has tipping increased?

[fnord_too]

I think the bulk of the reason is sociological. If I had to guess, I would say that the incremental moves are because (as has been suggested) people want to feel 'better' than the norm. If the norm is 15%, then 20% is 'better'. Also, I am sure this is pushed by the perception of what more rich and/or famous people do. I don't think this really goes on at a conscious level though. This seems similar to words and names coming in to and out of fashion with the masses to me. We are, as individuals and cultures, striving by large to be better than the norm, however we perceive better than the norm as being.