You can come up with endless scenarios to justify it, but the fact is you can't design something that will deal with all of them. So you design for the typical scenario.

Maybe there is an algorithm that boards a plane faster when there are 2 handicapped people, 3 drunks, and 1 person being late. But how typical is that? And is it realistic to design the whole algorithm around that? I would argue it isn't.

Real flights have those things in some numbers and a model probably ought to attempt to account for them, since, as you noted in a separate post I can’t seem to find now, they’ll affect the model negatively. The goal isn’t to find the best number of late people and wheelchairs. It’s to be able to board real flights as quickly as possible and every real flight I’ve ever seen, except the flight I took shortly after 9/11, has had some number of strollers, wheelchairs, or what have you.