

I don’t think is that. They have the data about you and me too, it’s just not shown like that (yet, at least).
Making those assumptions based on what you’ve bought from them is perfectly legal under the gdpr. Maybe you have to check a personalized ads option, or leave it marked, but I think that as long as you tell them in your privacy policy when they agree with it that your using their data for it you’re good.

Not exactly. Europrices are always after taxes, Muricans always speak of prices before taxes (and tip, if applicable), so just mentally changing the € for $ or vice versa gets you a good enough approximation.