Do all those other countries have America's population?
Why should that matter? As long as people are paying taxes it should scale up accordingly. That's how taxation is supposed to work.
Because Americans don't want to pay those costs to strangers especially with how big we are. In America, you only owe yourself to your family and your friends and strangers can get the finger, is it really any surprise Americans recoil in disgust when this keeps coming up? Especially successful americans who have alot of money or barely any money as it is?