Most of the time I wonder if the dev's at Apple HQ like to do things as my dad loves to say half arsed.. that is do exactly not enough to be perfect but just to get something to do something...A lot of Apple's stuff is almost perfect but for the lack of a simple finish.. You are left so frustrated..
Whether sending multiple files via AirDrop or copying and pasting multiple files, the same thing happens... Visually, Windows does not do this... Although I'm not sure whether or not they have the same behind the scenes implementation [files read and written all at the same time or one at a time]