Cheap ethnic food, our right or our prejudice?

I’ve often wondered why it is that we assume that many ethnic cuisines will be cheap. Why is this so?
For many people a cheap night out will often include a meal at an ethic restaurant be it Turkish, Somali, Vietnamese or Indonesian.
If you are talking about takeaway food then then the anticipation of thriftiness is increased. I suspect that the very early Chinese restaurants in this country were also subjected to this kind of prejudice but it’s amazing what a few generations of acceptance can do. These days many of the nation’s better restaurants are Chinese or more specifically, Cantonese and customers expect to pay a premium for this experience. It could have been the same prospect for those early Italian eateries, which are now such a far cry from today where Italian food is not equated with cheap, far from it in many cases. The dining public’s acceptance of more costly Japanese food has also changed somewhat over this time.
Paradoxically, Greek food until more recently has mostly been confined to the low price point threshold whilst conversely Indian food has always been on the more pricey side of the ledger. In the case of Greek food, I suspect unlike the Italians, that he Greeks had some sort of culinary cringe when it came to exporting their cuisine. This theory stands up especially when you consider that Greek cuisine eagerly absorbed many French techniques in their quest to modernise and be a part of a progressive Europe. Many dishes we equate being Greek actually are French in origin. This in itself is not as remarkable as many cultures enjoy pinching dishes from each other, however when you consider how almost primitive and basic the cuisine of Greece was, these additions must have been very seismic in their effect.
The fact that Indian food has always enjoyed a consistently high monetary value could be attributed to the fact that it is very familiar especially in England so it’s been absorbed over a couple of hundred years already, thus ‘doing its time’ as a cheap alternative and now has ‘earned the right’ to charge accordingly. These are all just my own views and are not based in any concrete evidence, just bits I’ve read and observed over the years.
Over the decades a few attempts have been made to ‘sex-up’ read,’ charge more’ for Vietnamese food. For the most part, this has manifested into the décor and fit-out of the restaurant. Banished were the cheap Formica tables and plastic condiments caddies and in were the bold statements of interior design. Linked to this was the notion of travel. Vietnam has been a hot spot for travellers for the last twenty years or so and people returned hankering for those authentic tastes. Throw into the mix a new generation of savvy entrepreneurs born with a sense of pride at their cultural differences and the smarts to know how to present and make money from them and you have a big shift in the dining publics’ perceptions.
Maybe one day the Vietnamese restaurants will be regarded as venerable as say those of France and Italy and then they can charge aptly?
However sadly I suspect that one new cultures' acceptance and sense of worth in their adopted country might even be defined by their entrenched price points in restaurants and cafes. Something to mull over and discuss I think.