No tipping is expected when using DME luggage delivery. Tips have already been taken care of. Tipping the bus driver is up to you. I have tipped when I had no bags for the driver to stow and have not tipped when I did have stowed bags! Why? Because the first driver was terrific. He was an excellent driver who gave us all sorts of area info along the route. He was hysterically funny, all while driving incredibly safely. He made that 30 min trip fly by. On the other hand, the driver who stowed my piece of carryon luggage (too large to keep with me on the bus), never opened his mouth when I got to the bus, gave him my bag and boarded the bus. He never welcomed us to the bus. BUT...when we got to the first resort, he made an announcement telling us that gratuities were gratefully accepted. Um....no. I will not tip merely because you took a smallish bag from my hand. You don't get a tip if you ask for one. And he left us sitting on that bus while he took all the luggage out at each resort. Those with no bags had to wait on the bus until everyone got off at once. He had his hand out, quite literally, as we got to our luggage. However his hand wasn't out to help older guests off the bus!!
And there is a sign at the front of the bus that states...gratuities gratefully accepted for outstanding service. I don't need to be told by a driver that I can tip him.
So, use your own best judgement when it comes to tipping.