[acdha]

The problem is that in the cases where you'd most want to, you never know what could be a problem until it's too late. Say in 2016 you went to a gay friend's wedding. No problem if that end up in some vast anti-terrorism archive of social media images since it's perfectly normal but … what about a decade later when President Pence of the Republic of Gilead declares that homosexuality is a crime against God and suspected sympathisers should have rights like employment curtailed?

That's an intentionally unlikely example but it's not like there aren't plenty of historical examples of this – e.g. imagine how much more dangerous HUAC[1] would have been if they'd been able to mine every picture on Facebook using facial recognition software to build a list of everyone who'd ever been in the scene with a targeted person.

1. https://en.m.wikipedia.org/wiki/House_Un-American_Activities...