I can't remember the last time I saw a grocery store without a sushi "counter". And they're all the same, west or east or middle, tiny store or huge. One or two bored asian people boxed into a middle-of-aisle four-sided counter, one side of which is a sad-looking case filled with the same boxed bland mushy hours old rolls. It's hard to imagine that it's that profitable, but clearly it is.
I think this is for different reasons, but most Americans don't fundamentally seem to know what good fresh fish tastes like, Sushi is no exception.
People whine and bitch about terrible food. I just eat it up like a happy camper.
Though taste is the most important thing to me!
I've noticed Vegan and Vegetarian restaurants get high ratings, I think it's because the potential audience is so happy with the fact the place even exists (and gives them an alternative to cooking yet another meal or fighting with yet another menu) that the default is a high rating. Even very mediocre places around where I live have 4+ stars.
Perhaps "Americans don't know what good sushi tastes like" though.