Also, to go along with the other points, it's not as if these kids you see in their wild Japanese fashions are dressing like that every day. They go to school Monday through Saturday and only get to dress up as they wish on sundays. Likewise, the adults who dress in more unique styles do so on their days off from work.
Most kids in America have a lot more freedom and can dress how they wish every day.
There are major cultural differences that contribute to why the Japanese sense of street fashion is so out there and crazy compared to American standards. It's important to keep in mind that not every Japanese person out there even dresses in those styles, in fact it is really a much smaller number than you would think. For example, when I went to Japan last year, the only time I ever saw anyone dressed up in styles like lolita, decora, etc was when I was in Osaka on a saturday night.