I don't think that most people who have had pizza from the top US pizza chains and have had a more "authentic" Italian pizza have trouble distinguishing the two. Italian pizzas are known for having thinner crust, a small amount of sauce, and more basic ingredients(albeit much more fresh usually), probably incorporates more olive oil, in contrast with something from, say, Pizza Hutt. American pizza has breadier and simply uses more of everything. A lot more saucy, a lot more cheesy. Don't get me started on stuffed crust! While there is a variety of toppings, most people go for a handful. Right now, zany combinations of toppings and sauces are popular, but people still most often choose pepperoni, sausage, "veggies", bacon w/ pineapple, etc. I don't understand how you can call it an impossible comparison; most pizza joints in America share very similar menus and kinds of pizzas.
Even pizza in New Zealand, when I lived there, was significantly different from American pizza. It's closer to American pizza, but Kiwis really love to use tangier sauces, which for some reason they also drizzled on to the pizzas. They even did this at Pizza Hutt.
Everywhere has regional differences. To claim otherwise is a bit blind, in my opinion. Just because American culture is mainstream doesn't mean that it's not distinct from other cultures it's related to.
> I don't think that most people who have had pizza from the top US pizza chains and have had a more "authentic" Italian pizza have trouble distinguishing the two.
That ain't the comparison being made, though. American pizza doesn't stop at Pizza Hut or Domino's. It includes the hole-in-the-wall pizza parlor with generic boxes and the ever-so-creative name of "New York Pizza". It includes the boutique shop with a proper stone oven and the thin crusts and "traditional" ingredients you'd expect from an "authentically-Italian" pizza. It includes hip vegan pizzas with cauliflower crusts. It includes pizza served alongside - or even incorporating - curry or kebab (side note: if you haven't had butter chicken pizza, stop what you're doing right now and find some). Hell, it even includes the "Bahn Mi'zza" I had for dinner a while back.
There are, in all, 70,000+ pizza restaurants in the United States, and that's just the ones that focus specifically on pizza - i.e. not including "Italian" restaurants as a whole, and not including restaurants that serve pizza as one component of a broader non-pizza-focused menu. All said and done, you've likely got more than a hundred thousand restaurants each putting their own spin - subtle or drastic, intentional or accidental - on the phrase "American pizza". That's in the ballpark of a 10:1 ratio of places serving pizza to incorporated cities/towns/villages/boroughs in the United States.
Point being, American pizza tastes - and thus the restaurants catering to those tastes - are so varied that "American pizza" v. "Italian pizza" ain't exactly a useful comparison. Same with Italian tastes, for that matter; not all Italian pizzas are the Neapolitan ones you're describing (prime example: Roman and Sicilian pizzas both feature thick crusts). Even regional comparisons are fraught with peril, but that'd be at least closer. Pizza is, fundamentally, a canvas begging for a painter to express one's creative vision upon it, be that a celebration of tradition or an exploration of new tastes.
Even pizza in New Zealand, when I lived there, was significantly different from American pizza. It's closer to American pizza, but Kiwis really love to use tangier sauces, which for some reason they also drizzled on to the pizzas. They even did this at Pizza Hutt.
Everywhere has regional differences. To claim otherwise is a bit blind, in my opinion. Just because American culture is mainstream doesn't mean that it's not distinct from other cultures it's related to.