It is a kind of racism to say American are immature. The general population in developed nations are immature.

Racism

prejudice, discrimination, or antagonism by an individual, community, or institution against a person or people on the basis of their membership in a particular racial or ethnic group,

This immaturity is the result of a life that does not challenge one to grow up, one that has little adversity. Most of the people in the developed world are "Snowflakes". Whine when the line at Starbucks is too long.

I won't lie, I was one and I was a slow learner, it took me a long time to grow up.

TEK