You hit the nail on the head, NM.

Although I get the feeling many people would still rush to be the first aboard even if there was guaranteed to be bin space for their single bag, since most Americans (and a lot of others) feel an irrational need to be at the front of lines, even when it's actually better not to bother. I think Brits and Aussies, by temperment and experience, do better with queueing up.