German Out-of-Home ads can now track your position (German)

The announcement: https://youtu.be/hoxPJRoNp34

> This is only possible because Adsquare's "OOH-Planner" evaluates data from 43 million smartphones in realtime in the background.

Okay, the tech behind this can almost be called trivial at this point, just like data integration with whatever their existing database was, but how in the hell is that not illegal, especially if they combine data into profiles? Even if they hide it in some pseudo opt-ini legalese, I remember a lively debate here in Germany around the time tracking garbage cans were deployed in London, and that was before GDPR was introduced.

Edit: Removed rant about developers at these companies, because the tech seems to be different than proximity based sniffing. According to PDFs [0] on their website they use app data from a plethora of platforms and get anonymized phone traffic data from a company called MotionLogic, which in turn seems to get their data from Deutsche Telekom https://www.t-systems.com/de/en/solutions/digitization/solut... - good job privatization, the then government based entity now sells your movement data to ad companies.

I really wonder how "anonymized" all their data really is after integrating all of their sources. Feels like an almost laughable claim.

[0] https://www.walldecaux.de/smartnet#download