It's never, to me a question of paying a bit more money; give me a smooth, as fast as legally possible journey & I'll happily pay a tip. But I hate being ripped off - plus - any driver that will try to skim you like that may also be the type of driver to do something far worse. I had a boss once who was taken into a rather unlit, dodgy area at night by a taxi from an airport (CGK) and a 'tip' was demanded with menaces.
Likewise I don't mind paying drinks for bar girls -but I don't want to buy a girl as drink & then be presented with a bill for an extortionate amount because I'm a gwelioh / farang / ang moh / matt selah / lao wai &c