No, they don't 'have to" handle my bag. They force it out of my hands because they want a tip. They "have to" drive the van to and from the hotel. If they are for some reason required to handle my bag, then that's their job, and what they get paid for.

If I get exceptional service from the driver, I've got no problem throwing a buck or two their way. But the late driver, or the one who acts like it's an inconvenience to be there, or drives the van like they stole it, etc? Nah...