Let me establish up front I'm as American as you can get, so I'm not some guy from outer Mongolia bad-mouthing the U.S.
I died laughing when I read your question inquiring about grades of olive oil in the United States. In the U.S. you get one grade of olive oil, it's fit for running lawn mowers — not for food. Our grading system is a fraud. Virtually all (thankfully, with the possible exception of olives grown and pressed in California) the labels on oils we encounter in our markets are figments of a marketing guy's imagination. Do you really believe an American label that says 100% Virgin Olive Oil or such baloney phrases (in this country) as first pressed, cold pressed, etc? In the united States it is perfectly legal to refine inferior oil and call it 100% Extra Virgin Olive Oil.
In Europe, by law, when you buy olive oil, or even beer, there are strict labeling laws. In the United States, our entrepreneurs invent whatever label sounds impressive to them. I don't know from experience, but I'm told that California growers adhere to strict, self imposed standards, and I suppose you can buy fine oil from them with harvest dates to guide you — but you'll pay for the privilege.
I go to Europe on business only because I have to — but while I'm there I taste olive oil like you only dream about here in the states. When you buy expensive olive oil from specialty shops, count yourself lucky if it's not rancid. In a word, olive oil is a crapshoot in the U.S.