If we compare California Chardonnays to the Bourgogne wines - I'm comparing price points, say, in the 20-30 range. In local wine stores and also in restaurants. They're the same price or more, unless you get something with a pirate or a dog or something on the label (although those are luxurious too oftentimes now).
I fully agree it's half the price in France. Even a 20 euro supermarket Bourgogne is worth 30-40 here.
My point is that the California ones should be much cheaper - there's no tariff.