Hilton is the programme where US members get the most of a leg-up with Diamond status by credit card. Beyond that I think Marriott does feel by far the most US-focused and myopic about the rest of the world (being constantly offered US credit cards, only seeing US contact numbers, being referred to as an “international member” etc). The various nights from cards do make it a lot better to be a US member than a foreigner, but at least at the Ambassador level the spend requirement provides some form of level playing field (even though nights mean I’d have met the requirement if I were a US resident). So definitely not fair, but it could be worse and it’s pretty much up to them.
The only thing us internationals can hope for is for the US credit bubble to burst again as soon as possible and destroy the current credit card points system over that side of the Atlantic.