If there were no good local substitutes you have to pump up the grease and toast the ingredients a bit more to make it flavorful enough.
Given that these places served a lot of immigrants when they opened, I also wouldn't be surprised if it helped having a sturdier pizza that you could take to work with you.
As for the ingredients, I’m not sure why Italy would have inherently better local ingredients. I can understand why northern Europe has shitty tomatoes (too cold to grow compared to, for example, southern Italy), but with its size, population and diversity of climates I imagine you can grow pretty much anything in the US at a decent quality, without the need to grease stuff to give it flavor.
It's also possible to live among wheat fields and not be able to buy good bread for anything less than insane luxury food prices here. All I can figure is our ovens cost more to run? I mean I know it's not that but I can't figure out WTF else could be the problem.
Decent cheese is also a lot more expensive—but again, we have lots and lots of fairly bad but very cheap options. And the cheaper end of our wine market is (much) less consistently good than in, say, France.
You could grow anything in the US and there are indeed great producers for everything. The problem is recognition.
PDO/DOP Parmigiano, prosciutto and olive oil and san marazano tomatoes are in the you cannot do wrong cathegory. They are always excellent.
A pizza maker in the US will have a lot harder time discovering great ingredients made in US. Not because they don't exist, but because anyone can label almost anything.
I believe this is true, subject to the original source material (seeds?) being imported.
> but with its size, population and diversity of climates
This makes it tricky, as producing enough of the high quality ingredients in appropriate locations, that can survive the transportation distances, creates a whole new range of problems.
Solving this at Italy scale is a different matter to solving this at USA scale.
Italian cuisine is all about letting the ingredients speak for themselves and success really depends on having high quality ingredients. So, yes, selecting for tomatoes that have long shelf life and trucking them long distances would violate Italian food sensibilities.
The Italian point of view would be to make the most of the ingredients that are available where you are. In other words, if you don't have fresh tasty tomatoes in the middle of winter, don't substitute subpar global-supply-chain tomatoes from the supermarket. Instead, use something else, like high-quality sundried tomatoes or don't use tomatoes at all. This is what happens in Italy, and it's why what visiting Americans might consider "iconic" Italian dishes aren't always present or recognizable.