Summary: Except for auto dealerships, retailers don't use personalized prices.
What a terrible article:
1) Its first example of "personalized pricing" isn't actually personalised: it was the result of an A/B test.
2) It says 'Outsize profits can be extracted from “top of the demand curve” customers' when, in fact, the top of the demand curve is normally when price is zero. The author seems to acknowledge this as they reference 'the downward sloping demand curve highlighted in Economics 101'.
3) The only convincing example given in the article is that of 'auto dealerships', which are the least typical retailers there are. People hate going to auto dealerships, but they love doing other types of shopping, in-person or online. Part of the reason is the personalized pricing (and process of haggling), but this has existed for many years, and the rise of the internet has actually made it easier for consumers, not harder, to get a reasonable deal.
4) "A key question is whether personalized pricing, on the web or in-store, is ethical." A better question would be 'How do retailers use personalized prices?'. That's the question I thought would be answered, given the title. The author's answer seems to be "Except for auto dealerships, they don't".