Haha, I found that really weird too when I first arrived here. xD You get used to it though. Japanese are polite in most situations. It’s all about social context. It’s so crowded in Tokyo (and being packed together is so common) that pushing and shoving becomes kind of normal and acceptable. People push past each other on the trains, in stations, in stores and queue relentlessly. It’s just what you gotta do if you want to get what you want and where you want.
That, and Japanese are freaking serious about sales. (O_O;) I’m surprised more people don’t get injured. If they did Black Friday here I think it would double Japan’s crime rate. xD The New Year sales are probably the closest equivalent, but thankfully most stores anticipate for it so everything is pretty well-organized to minimize the spilling of blood and the slaughter of tiny children. Smaller stores (such as Closet Child) are not so well-organized…and lolitas don’t care who they trample to get what they want. Survival of the fittest! (ノಠ益ಠ)ノ
You’ll find that everyone politely ignores each other whilst trampling though, much like you would ignore other people in a crowded elevator despite having their elbows shoved in your stomach and the ends of their hair tickling your face.
…In conclusion, people are weird, but as the Japanese say, “Shikata ga nai.” - “There’s no other way.”