Bomarc
.. and of course, people are infallible
Looking back at the developments since I started flying (ignoring FMC's, map displays, reliable engines, Cat 3 ILS's etc), for me the two most significant are EGPWS and TCAS - both of which are technology items.
If you want to introduce a human element, how about not giving a landing clearance when you are #9 at 40 miles? The US of A may shift more 'tin per km3' than elsewhere, but it really could do with looking at 'best practice' elsewhere rather than thinking 'we are the best', you aren't necessarily. You may be at some things, but your culture leads you to believe that because you are #1 (for the moment) most powerful nation, that you must know best.
This, to me, is just as bad as the Far/mid Eastern 'the captain knows best' attitude, where a co-pilot will not speak up and let the aircraft crash rather than criticise a more senior pilot.