https://techcrunch.com/2021/11/12/techcrunch-roundup-collecting-zero-party-data-airbnb-ceo-interview-crypto-volatility/

Back when most commerce took place on the local high street, shoppers who exchanged personally identifiable information with merchants received something in return.

Shops kept track of customers’ hat, shoe and dress sizes, along with their birthdays, anniversaries and personal preferences. In return, buyers got a first look at new products and service that anticipated their wants — personalized shopping.