Is it because it works on patterns and your random garbled string would have too much noise to be compressed well, while a structured file coming from an actual piece of software would probably have enough repeating patterns to the point where it actually can be shrunk?
Flatbed with cheese and tomatoes on pizza bread… Yep, that’s basically pizza. You can say Italian Americans evolved the dish and created popular varieties, but the basics come from Naples. Flatbed with toppings was eaten even in Achaemenid Persia, so I’m not talking about just that, but about a dish called “pizza” with cheese and tomatoes, and that clearly comes from Italy.