That isn't a fair comparison, as there is a massive difference in the quality of hole-in-the-wall ramen in Tokyo and a $2 fast food chain hamburger in the US.
I guess the issue is that fast food in the US is pretty protein-centric, which is fairly expensive for good quality. I'd probably take the hole-in-the-wall ramen personally but I can't think of any typical US "fast food" that lends itself well to inexpensive quality.
Good ramen isn't that cheap or easy to prepare but the time and ingredients required to make the broth can be spread over a lot of servings.