Have mixed opinions on this. Very complex (and sensitive) issue.
Fire away. This is VT, anything goes.
Might have something to do with how rapidly those societies are changing. You get people who have acquired large amounts of wealth in a very short period of time, but still have the mentality of someone from a lower social class, and thus lack intuitive knowledge of the social etiquette that is expected in societies that are economically more well developed. I don't know, just a hypothesis at this point in time.
Sensitive, because it is politically an extremely sensitive issue, esp in Singapore. Mixed opinions, because while I do agree that these migrants often tend to be rude and uncouth, I understand at the same time that that is in all likelihood due to the fact that they are a product of their environment, which is different from the relatively affluent one I grew up in, so I try to accept them more than others generally would. Not to mention that I identify with them (as a Chinese person, and as a fellow human being), and so I try not to complain too much about their habits, whether I like them or not.