Agreed Redpossum. I have waitress friends here who are single mothers and who carry trays full of heavy ceramic dishes, silverware and full glasses up and down a flight of narrow stairs for eight hours a day, five days a week, to take care of their children. And sooner or later they take a tumble. So I am incredulous that there are those anguishing over whether or not to leave a 10% or 15% tip. It's not like people here are dropping $400 USD a meal as they would at Le Bernadine. And to count out a 5% tip for a delivery person. Really? That reminds me of the Judge Smails character in Caddyshack. My philosophy is that I take care of those who take care of me.
By the way, in Santa Cruz, Bolivia it was not uncommon for unrequited trapitos to occasionally to remove and sell a tire or a headlight to send a message.