Speaking as a Canadian, I can tell you that 1) cultural diversity is an invariably positive force in any society
This sounds like a fragment of a speech from an ethnic festival. The fact is that cultural diversity has its ugly sides too and it is not so "invariably" positive.
2) Asian cultures are *extremely* disciplined and value strong work ethics above all else.
Yes, they are disciplined by their governments on a fairly regular basis as soon as they don't fall in line. The phenomenon is also known as "human rights abuses".
Other than that, some are hardworking, some aren't at all. Based on direct experience I can say that Asians (including Vietnamese) are perfectly capable of abusing the system like a national of any other country.
I think it's too late for Poles to claim some monopoly on suffering. Another nation has already established a monopoly in this business.