I used to work at the HSBC tower on Sathorn, in the heart of Bangkok's financial district. There was a simple open-air shack just outside that served (IMHO) the best pad Thai I've ever had at 25 baht a plate, and the place was packed every day with everybody from suited bankers and lawyers to tuk-tuk drivers. I don't think I ever saw another farang on there though.
Also, proper pad Thai is not spicy, like all noodle dishes in Thailand it's supposed to be served with condiments (chili flakes, phrik kii nuu in fish sauce, sugar, ground peanuts) so you can tweak the flavors to your liking.
I'm sorry but what on Earth are you talking about? I can only assume you have simply never visited Thailand? This is just so inaccurate I don't know what to say.
In tourist hotspots (which abound in Thailand) you'll tend to see picture menus and Pad Thai will be on them. But there are much, much better dishes to be had outside these areas. One issue is they don't all have consistent names, e.g. when I asked for a recommendation and was given an absolutely amazing dry curry crab noodle dish with egg, I asked for its name in Thai and translated it was "curry crab" which would never get you a similar dish in another restaurant. Even the venerable Pad Kee Mao, which I think is always a noodle dish in America, is sometimes a totally different rice dish in Thailand.