Why are American woman so awesome and easy to have with?

This is something I recently started wondering. It's not really a bad thing and kinda cool for guys that travel to the U.S. I went to the U.S for about a month and it was great. I went clubbing and had with multiple woman. They were so easy and gullible but the only question I have is why? Woman in other countries are much more difficult to have with but Woman in America seem to be really open! Is this because they just love having with many guys or is it because they are just so easy to fool around with? Do American woman lack self esteem or do they just love foreign guys?