It's not only Google, FB and data brokers... consumer goods giant Procter & Gamble says they harvested 1.5 billion consumer profiles, linking devices, names, addresses.
'First party' marketing surveillance: adexchanger.com/online-adverti…
crackedlabs.org/en/corporate-s…
Device IDs are 'personal data' in the EU. Even when they use hashing to 'anonymously' link them to other data it's still about personal data. He states they get IDs through 'media buying' and 'linking with publishers'.