If this was any country other than the US I couldn't do as well. I might be ok at Canada, and maybe a bit of Mexico, but I would fail miserably at any other country. I wonder, probably wrongly, if the world knows more US states than Americans know of their states. I also wonder if California might be the most well known state in the world. Again, most of this is probably because of my western (and Californian) bias.
The rest of the world, to my knowledge, doesn't value statehood like we do in America. We are really 50 nations bonded together as one United grouping. That's how we started out as,how we were until civil war, and honestly how we still are.
We are bound to the Constitution which requires supermajority of states voting to change. States still have national guards and militias. The concept of the Senate is founded on the idea that states will perpetually have significant weight in government. Otherwise San Francisco, New York City, and Chicago would shove their liberal views down the throats of rural America with no concern for the values of the people there. Even becoming a state is extremely difficult because of how valued it is.