Way back in the dark ages (1944 I think it was) some hopelessly naïve and starry-eyed people got together and formed an organisation to encourage states to adopt a common aviation system. Among other things it would allow license portability across national borders.
They called it ICAO.
Pity Fortress Europe and Fortress USA don't want to play these days.
But quite why the FAA is so resistant to change is beyond me
I can help you with that BEagle. Modern USA was settled by (mainly) Europeans. Unsurprisingly they inherited a European attitude to change. Present company and all PPRuNers excepted, naturally.