I don't tip my doctor or my dentist when I get my teeth cleaned and I don't tip cashiers when I buy groceries. However, I tip just about everyone else because having driven a taxi at one time in my life tips were a good part of my income and greatly appreciated. I remember in the early 1970s Australians would never tip because it was not a custom in Australia but they eventually learned to do it and became very good tippers. The French, on the other hand, could not be excused for their failure to tip because tipping was a common practice in France and they knew better. Also, I tipped in France, so it really ticked me off when they refused to reciprocate. Anyway, I tip my barber a hundred baht for a 120 baht haircut and just about everyone else, even jitney drivers.