i think the US system is probably better for wealthy people who always use cards and actively play the game (and for the credit card processors of course). Euro system is better for everyone else
ps: is there some sort of contract that stops vendors from adding a "credit card processing fee"? maybe banning those clauses would be the best way to let market forces sort the issue out - once people see that they're paying 3.5% more to use a 2% cashback card, they'll start asking for other options