Nope. They almost all have real cheese. Usually a mild cheddar. It's then melted with sodium citrate and pasteurized for a longer shelf life (while still being creamy and tender)

It tastes slightly more tart than straight cheddar, but that's it. Well, slightly more tart than a mild cheddar. A sharp cheddar is just as tart, but it's a slight difference in flavor.

Potentially information bleed over. You can use some American Singles cheese to smooth out cheeses in other dishes because it contains emulsifiers (I think, or another compound), but Nacho Cheese is a specific kind of cheese that should be free of American cheese byproduct