There's a big difference between the Thai food made by Chinese in the US and Thai food made by Thais.
And also if you happen to have a restaurant with real Thais that 'Americanize' the menu, you can always ask them to make it authentic like it is in Thailand.
I would say that a good majority of the 'Asian' restaurants are Chinese owned and operated, and that can make a difference when I'm looking for authentic Japanese or Thai food.
This is easily avoidable in big cities.