I think the point is they are very different cuisines, not interchangeable. They both just happen to be spicier than the American palate is used to.

I don't choose food based on country of origin but what I fancy to eat. Sometimes that's Indian foods sometimes thai, sometimes vietnamese etc.

I live in Australia where there is not a great selection of Indian food (despite a relatively high Indian population) compared to the UK where I also lived. Even so, there are different styles of Indian food with different dishes available just in my suburb. It's nothing like Thai food, which also has a large variety. Both Indian and Thai restaurants have a few dishes that are 'classic' and available at most mainstream restaurants. Like, it would be odd to not have Pad Thai available, or in an Indian, butter chicken.

Sometimes I'll want a pad Thai. Sometimes a butter chicken. The pad Thai is not better than the butter chicken. A green curry is not better than a jalfrezi. They are different flavour profiles.

I would say there is more crossover between dishes from Vietnam, Thailand malaysia and China, with varying levels of spice and flavour but very similar dishes available and common.

Again, you might prefer a Vietnamese sweet and sour chicken, but that doesn't mean Cantonese or Hong Kong style is better or worse.