It’s true that Italian olive oil has traditionally had a lot better marketing. When we talk about p70 and p80 olive oil quality, Spain wins hands down over Italy and other producers. Don’t get me wrong, Italy and Greece have excellent olive oil too, but it’s much harder to find and usually a lot more expensive. If you’re at a supermarket and have to decide between Italian and Spanish olive oil, chances are that the Spanish olive oil will be much better and, sometimes, even cheaper. A common practice in Italy, even though they don’t like to admit is, is that they import Spanish olive oil, relabel it, and sell it as their own.
One thing Italy, Greece, and other parts of the Mediterranean have is different and more diverse olive tree varieties. Frantoio is a good example.
The most important thing when buying great extra virgin olive oil is to buy straight from a well-known producer. If you buy from an intermediary, the chances that they’ve cut the EVOO with other oils (a common practice in markets outside of Southern Europe, like the US) to cheapen them is high.