Tipping is *so* weird, isn't it? It can be tough to figure who to tip, how much and when...
Before I purchased my own personal mobility device that I travel with now, when I would rent an
ECV from an outside vendor (like Walker,
Buena Vista, etc.) if I happened to be there when it was delivered, I would typically tip $5 - just because even if I could get up in the back of that truck, you would have to pay me more than $5 to get that thing down to the ground LOL
Again, if the driver was there at the return, I would pass him/her $5. It isn't much - really just showing my appreciation for them being on-time and courteous more than anything.
You don't *have* to tip these people - it's not something that I would do ordinarily. But for me, that rental ECV made such a HUGE difference in my ability to enjoy Disney World, that I happily tipped them.