US carriers all "throw em in". Actually throw the bags on a conveyor, and somebody in the baggage compartment throws em in. I haven't seen anybody do it different in the US.
Airbus seats are wider than most Boeings. I think the 777 they are the same as Airbus. The problem is the Airbus operators have never been able to monetize that extra seat width. Very few coach passengers take time to look what type of aircraft it is. They click on the lowest price. In effect, they have been giving away extra seat width, at the expense of - extra expense. Extra weight, extra drag. Coach passengers also don't pay extra for a quieter cabin. I personally like big seats and a quiet cabin, but if the passengers are paying for it?
I am one of the few that will pay extra. I will pay extra to fly on Jetblue. AB seats, an extra inch of seat pitch, and Live TV. I would pay extra.