I have often compared to see which national food in the USA comes closest to the real thing... that is, closest to the food actually served in the country it hails from.
I'm not sure. But here some 'off the top of my head' opinions: (and note, only using countries that I have visited)
Italian in the USA vs Italian in Italy - not very close at all. Huge difference.
German - somewhat close. However, there are VERY few German restaurants.
Japanese - not very close... I think closer than Italian but not by much. HOWEVER... Sushi is VERY close - it's the other dishes.
Chinese, (actually I have never been to China BUT... I'm going to add this because in Japan there are perhaps MORE Chinese restaurants than Japanese restaurants). Similar... but still not very close.
Mexican - well - if you go to Mexico and stay very close to the border with the USA it's actually quite close. If you go south of the Border then not so much.... in fact, VERY different.
French... I haven't spent a whole lot of time in France... but I have been all over the country. French food is VERY highly rated, and I don't get it, except in the Normandy area... the food there is FABULOUS.. in Paris, and Southern France? Eh. Lot of horse meat. But as to similarity - somewhat close compared to most French food... not close at all to the food in the Normandy area.
Canadian - didn't know they made food in Canada, did you? Ya gotta be very near the border in the USA to find Canadian dishes... and it's worth it. Same here as there, and both excellent. Mostly 'stews'.
In summary... food here in the USA, no matter how it's labeled, is food here... and for the most part not very similar to what you'll find in the native countries they hail from. And as you would expect.. it's ALWAYS, no exceptions, better in the country or origin. But that isn't selling the USA short...
Good Ole' American food is as good as it gets. Lead me to an all American diner in any state in the Union and I'm a happy camper. - JamesJM