If two consumers purchase the same item at the same time, it should be the same price. That's what we're debating. If an airline raises prices closer to departure, then that's not a violation of privacy, nor discriminatory in the sense we're discussing here.

I do, however, object to firms aggregating any individual's purchases across different interactions. That data should belong solely to the individual and it should be illegal to retain enough information to aggregate interactions across interactions with the same customer.