Anytime someone touches my bags, they get a tip. If the DME driver has had to stow my bags under the bus, then he/she gets about $1 a bag. If I have just ridden the bus, holding my carryon bag in my lap, the driver doesn't always get a tip. See, the thing is this....there has always been a sign in the front of the bus saying that while not mandatory, gratuities are most appreciated. Okay..I have no problem with that. But, if the driver then makes a comment about the 'tip policy' I give them nothing. It seems like begging to me. If the driver has done a nice job of making the ride more pleasant for me, then they get a tip. But to drive the bus, silently, not touch my bags, and then make an announcement saying that gratuities are much appreciated? Nope, don't think so.