You’re not wrong about individual agency and privacy. If you post information to a public platform and cry foul about privacy when someone asks if it’s yours, that’s on you as an individual.
Since we, in the US, have no codified right to general privacy, it’s on us as much as possible to protect it and be aware of what we put out in public spaces. You never know when someone in power might choose to abuse the expectation of privacy, whether it’s an elected government or a private corp.
Did you read the article at all?
Regardless, this shouldn’t come as a surprise; the UK has been a surveillance state, at a minimum, for decades.