North America is a continent. South America is another one. And even if you just take the US, it's functionally a continent due to its size. You get the same diversity as a continent because it's continent-sized.
The UK has far, far more types of crisps, cakes, and chocolate bars than the US does. In the US, you can't get Smarties, Fry's chocolate cream, Turkish Delight, chocolate buttons, Crunchies, Twirls, Flakes, Wispas, Picnics, Milky Bars, Minstrels, Maltesers, Lion bars, Boost bars, curly-wurlies, and god knows what else. These don't exist in the US, and there are no equivalents. We have about five chocolate options. For crisps, it's Lays (Walkers), Pringles, or Doritos. You can't get Discos, Skips, Frazzles, Wotsits, Hula Hoops, Monster Munch, or Walkers Sensations. And there are virtually no cakes, not like the UK where we have Kipling's etc.
Last time I was home, I took a photo of a couple of aisles of Sainsbury's to show my American friends. An aisle packed top to bottom, end to end, just with crisps. Same another with chocolate. You do not see that in US supermarkets, which isn't surprising since the UK has way, way more options in crisps, sweets, and cakes.
In the US, the snack aisles are full of peanuts and other nuts, and SO many different types of crackers.