worst of all, considering that public debate and administration should not be between individuals, but between "cultural communities".
That's nothing new. I don't like it necessarily either, but it's not an exclusively multiculturalist sin. Think of religious leaders who claim to speak for all Christians or Muslims or whatever, or CEOs of XYZ corporation claiming to speak for the "business community", or even unions speaking for their members. If businesses or other lobbies are able to aggregate into blocs to make themselves heard in the public sphere - even if they don't really speak for all they claim to speak for - then why shouldn't "cultural communities" be granted the same privilege.
Let me guess, the Victorian police are you watching to make sure you treat them Burmans right.
Paying Burmans 1/20th of the legal minimum wage is an integral part of Thai culture. If anyone ask it's reparations for Ayutthaya.