Tipping the performer in America is only done as far as I know in venues where the audience has not paid an entrance fee. So this usually means a bar, pub, restaurant, coffeehouse, etc. I've never seen it done at a concert. At most bars or pubs, it's expected that the performer will have a tip jar on stage within easy reach. I've played at pubs and occasionally forgotten to put the tip jar up and people would come up to the stage and ask where it was. There is no assumption on the part of the tippers that the performer isn't being paid a fee, the patrons tip to express their appreciation if they have enjoyed the music. Sometimes they'll tip after a particular song they like, or sometimes they'll drop something in the tip jar as they are leaving. There is no obligation and I've never seen a performer (except jokingly) try to solicit tips. Tips can really add up over an evening if everybody is having fun. Sometimes the tips can be almost as much as the fee. I don't think it is patronizing when people leave a tip. They just want to let the performer know that they enjoyed the evening's entertainment.