What’s interesting is that Thai food in some east Asian countries is considered fancy and the price reflects that while in North America most of them (but not all) are the affordable kind —that is on par with other non-fancy food joints.
In Australia it is similar. Roughly speaking, the following cuisines have these types of price ranges:
Indian: $-$$ Chinese: $-$$$ Thai: $$ Japanese: $$-$$$ Italian: $-$$$$ French: $$$-$$$$ Local: $$-$$$$
It seems that Asian is fairly set on low-mid, while European can go higher and still do well. Same with Japense and Chinese. Italian has been so integrated into the local cuisine that you have very cheap to very fancy. French is rare so more expensive. Japense also rare, though sushi train type places are becoming more popular (though still on the pricer side).
Chinese: $-$$ Tex/Mex: $-$$ Indian: $-$$$ Thai: $$ Japanese: $$-$$$ Italian: $-$$$$ French: $$-$$$$
Note: Tex/Mex, Italian, and Japanese availability, quality, and pricing vary widely according to where in the country you are.
I'd chalk up French to the 1980s. As in "If you wanted to be a really good chef, you studied French cooking", which resulted in popular "If you wanted to go to a really fancy restaurant, it was French."
Thankfully, that seems to be fading in the urban US in favor of more local/fusion emphasis.
Not enough fancy Thai places though, only 1 really unique one in all of the Seattle area to the best of my knowledge.
1. Dong Ting Chun is really good.
2. Liuyishou Hotpot.
3. Núodle has some good dishes.
Cheap places are "Australian Italian", usually with incredibly generic menus and large servings of bland food. That's your Lygon Street Italian, if you're familiar with Melbourne.
Expensive places usually serve "Italian Italian".
For contrast, here's Universal's menu, which is a "Lygon Street" Italian restaurant: https://www.universalrestaurant.com.au/menu
Compared to nearby Tipo 00, what I would probably consider to be more authentic Italian (although still not 'expensive'): https://www.tipo00.com.au/food/
There are also significantly better inauthentic-Italian experiences around, like Capitano which takes its cues from Italian-American food culture.
Logic being a couple sushi rolls for lunch type thing is about as cheap as it gets and these places are everywhere.
Italian seems more bimodal, you have cheap pizza joints and sandwich/sub/hero shops and you have the white tablecloth places. Japanese is either $$ or $$$ (in rest pricing parlance). But rarely do you get cheap Japanese or cheap Korean though Korean rarely goes to $$$. (maybe LA has super fancy ones) Indian mirrors Korean. I think they kind of loosely mirror the economics of the population that brings the cuisine and those that give it their patronage.
At least where I'm from there's bimodalism in Japanese cuisine if you count sushi rolls, which can be had dirt cheap (pretty localised/internationalised though). I like cheap sushi here because the cheap sushi game is usually locked down by koreans, so the rolls end up being this blend of kimbap and sushi rolls.
Dunno about Korean restaurants in the west though, have only been to Korean restaurants in Korea.
edit: Wish I was from/lived some place with nice cheap Italian sandwich shops etc, that must be amazing.
To edit further, I think western consumers' perception of a country (as well as what you said about the country's population) affects price as well
Scale used: $ (<10€), $$ (10-17€), $$$ (18-45€), (>45€).
I went to Thailand a couple of a years ago and visited a restaurant in Bangkok that was supposed to have the best pad thai in the country. It was decent, but I've had better in the UK. The best thing about the restaurant was that every table had a pot of peanut dust that you could add as liberally as you liked to your meal.
Tastes differ on which variations are best, but I agree with the ground peanuts (and lime and pepper powder and ideally served with cucumber slices...)