In my opinion, this is a result of the poor baggage handling services provided by airlines in the USA. Since it takes such a long time for checked bags to be delivered to the carousel after arrival (I waited 55 mins on Thursday for the first bags to be delivered on arrival into MIA, and after 70 mins it became apparent my bag was not there - it was delivered to me 14 hours later!), travellers in the USA have become accustomed to avoiding checked bags if at all possible.

By not checking bags, people end up carrying on large bags (often more than one, even though there are now restrictions), causing great contention for overhead locker space. That causes people to want to get on board as early as possible in order to secure overhead locker space. So the airlines have had to honour the desire of their elite FF members to board first so they can secure overhead locker space.

And if they boarded the rear rows first, the rear passengers would fill the forward overhead lockers making it a real mess when the forward passengers are forced to squeeze their bags into the lockers behind their seats. So upon arrival we would then have people trying to move backwards down the aisle to get the bags.

I find the situation in Australia (my home) much more civilised. Checked baggage service is generally good, with bags arriving at the carousel within a few minutes of the passengers. Carry-on luggage is strictly enforced for size (not so often for weight), resulting in minimal contention for overhead locker space.

Since there is plenty of overhead locker space, people sitting aisle seats or in the front cabin (more appropriately named business class on a domestic flight) don't want to board first, but prefer to spend more time in the lounge and board last knowing there will be plenty of space for their carry-on bags.

As a result of all of the above, boarding is generally called by row numbers, starting from the back of the cabin. Business class passengers are free to board at their leisure. When I am in business class I prefer to stay for another drink in the lounge and board after the queue has died down, rather than rushing on board just to end up sitting watching the rest of the passengers walk down the aisle.

When I travel in F in the USA, I get on-board early, knowing that the overhead bins even in the F cabin will be filled!

So I believe this is a USA cultural difference, similar to tipping. When in the USA I follow the local boarding process just as I follow the local tipping culture. But I prefer the system back home (regarding both boarding and tipping).