That does make a difference. Kids in rough areas or from unfortunate backgrounds really respond well to being put in uniform. It makes them feel like they belong, and they like having clear boundaries set regarding how they're expected to dress (as well as general behaviour). It's like flicking...
No it's not. It's called discipline and conformity. There's a time and a place for dressing in an individual way and being a bit whacky and non-conformist: University. Then when that's over, you need to go back to conforming a bit if you want anyone to take you seriously career wise.