*snickers at the thought* If we equate the driver to being a host of the trip because he/she is paying for all the gas, then he/she should anticipate the riders in the car will be tired after a long day of hiking and should be required to provide pillows, blankets, eats and drinks for the car ride home.
And I don't think anyone has ever said that the host of a party should anticipate any and all possible needs of guests and be prepared to accomodate them.
Although yes, I would think that it would be nice if a driver realized that people will likely be tired after a hike, and at the very least didn't set up the expectation that they would not sleep.
My point is, someone freely offering hospitality (in this case, by insisting on driving and by refusing money from other passengers) is doing it because being nice to others, hosting them, gives him pleasure and satisfaction. To be a host means that you give no expectation of getting anything in return.
Even if you really do, because politeness says that this is proper on the part of your guests. If the driver of the car is the host in this case, then yes, a nice "thank you" of some kind is in order from his passengers. A nice card, maybe. And he'd be well within his rights if he came to a board like this and expressed that he was frustrated, if his passengers never thanked him in any way.
We don't send invitations to our own wedding out with a note that says "you better RSVP properly by the given date and you better not add any extra people or you are a thoughtless social misfit and I will call and scream at you" although yes, we do expect our guests to respond properly by the due date and not add extra people.
And by the same token we do not include a note in our gift to an HC that says "you better send me a handwritten thank you note that specifically mentions this gift and what you're going to do with it even if you hate it and are just going to stick it in the garage and hope the next flood ruins it, or else..." No, we don't do that, though we do expect some kind of thank you note, hopefully a proper one.
That's more what I'm getting at.