But I've read so many times (on French forums) people argue that Apple is overcharging EU citizens by forgetting to adjust for sales taxes that I defaulted to interpret "In Europe Apple stuff costs much more" that way.

In a way it makes sense, in France what you see is what you get, so the typical French consumer expects the sticker price on the US Apple Store to be the final price. In fact it's the law: in France you have to honor the sticker price, even if it's wrong (unless it's an obvious mistake, but the bar for obvious mistake is quite high).