I'm never sure how people manage to invent some sort of benefit with how the buses load. I've also never seen these mythical parties of "ten" that everyone talks about.
As the previous poster said there isn't a benefit to boarding in a wheel-chair because every-body waits at one end. Able-bodied people wait while the wheel-chair party boards and the wheel-chair party waits while you unload. Everyone waits on one end of the trip or the other, so I'm not seeing where this benefit is
It makes sense for the wheel-chair users to board first because they need room to maneuver into the tie down spots. It doesn't make sense to leave the tie down spots empty because each bus can only accommodate two chairs max. Back-logs can get crazy enough as it is now, trying to board a bus in a wheel-chair. If an able-bodied family sees 6 people in front of them they know they can get on the next bus, if a wheel-chair user sees 6 people in front of them they know the best they can hope for is to get on the 4th bus,