What is unsaid is when a Canadian worker in US gets laid off or just decide to leave (s)he is just moving in first world. Apart from less pay, living standards are pretty much same in US and Canada. But if Indian worker gets laid off it will be drastic change in living standard by going back.

Even very high Indian salary would not buy that US lifestyle. Of course many people will like to couch that fact as having friends' circle in US, kids schooling etc makes it difficult to relocate.