You made a blanket statement and I called you out on it, you need to be careful because you can come off sounding like you are racist or hate a group of people when you actually hate some specific about them or specific people.
You also have to put yourself in their situation. They don't really know anyone and probably have little knowledge of our culture and they don't speak the language so well, I'd probably be hiding in the stairwell as well if I were them, or at least I can understand why they would. Yeah it's a little creepy, I'll give you that, but I wouldn't hate them for that.
As far as the rude kid, well maybe he just didn't have money to buy a ticket or maybe you surprised him and his reaction was to be rude, or maybe he wasn't trying to be rude but he didn't know how to put it delicately that he didn't want it.
I'm sure there are plenty of people that live in this country that don't support their schools well, so we just pick on the foreign ones that don't and tell them to go back to their respective countries? Seems rather hypocritical.