Similar to KYC (Know your customer) [1] in financial services industry. We need Know your Data Broker for customers, where in customers can know which data brokers have used their information. Most of the data brokers run in the dark and very few outside of tech are aware of it. Data Brokers should allows customers to be opted out and purge information from their systems if needed.

[1] https://en.wikipedia.org/wiki/Know_your_customer