I run into similar situations with Mexican food. I live in a predominantly white and rural community and there's a Mexican restaurant right next to where I live that's really popular. First time I went in there I got their spiciest options and when I asked if they had anything spicier they said "sorry, we don't have anything spicier. We're trying to make it spicy for white people." I was a little disappointed, but I also totally get it and we both had a good laugh about it.

If I had to loosely spot a guess, the American options probably don't use curry. Curry tastes freaking weird spicy yo, it's certainly an acquired taste..