Italian here. I don't think we really want to "keep the best produce for ourselves" - I'm sure our producers would just like to sell at the highest price. Instead, there is a problem with transportation and timing: if you harvest well-ripened tomatoes, they spoil quickly, which is something big distributors hate. Here you can usually find the best tomatoes in small markets in the right season; tomatoes from big supermarkets are usually pretty tasteless (unless you get lucky or know how to choose).

It's the same reason people tell me that bananas in banana-producing countries are way better than what you can find here: our bananas ripen during transportation, and the end result is very different.

PS: it's much easier to find very tasty cherry tomatoes, but they're also much more expensive.