Why are U.S. women so rude?

As you can tell from my name, I come from the Netherlands. I came here for two weeks due to my job, specifically to Colorado. Allow me to say that the women over there are extremely rude. In the Netherlands and most of Europe, both the men and women hold open doors for one another as a sign of politeness and respect. However, in here whenever I enter a door the woman in front of me does not bother to hold the door open, rather just slamming it in my face like some animal. The men, however, including myself despite nothing in return of course, did hold doors open for both men and women. This happened countless of times. I also witnessed four times, when I entered a shopping mall to buy gifts for my family, a girl slapping their boyfriend/husband, and not in a playful manner. It may not seem like a big deal to you, but United States women just in general seem to be lacking basic respect and manners, especially to men. They act like they are superior individuals. I am back home in the Netherlands now and I can't say I am glad enough! Why are U.S. women so rude, in particular to men but also to women sometimes. I guess the song "American Idiot" wasn't lying!