When they are compelled to do it, they will not even know it is happening. Only the people doing it would know. That’s the reality of why it is done now. That there is a market for it should never have been allowed but the capability is necessary to troubleshoot the network. I guess it seems silly to say this is even a legal issue. They shouldn’t do a lot of things, but they are going to be legally compelled to do them, so the network structure’s form follows that function. If there is no market for that data, they will get the data by proxy by leasing access to the network or the customer or the metadata for security or other legal purposes via intermediaries or separate internal units. This is just how ISPs have to handle this kind of data request or other legal request. They have formal means to ask for what they need, and they will usually get enough data to find out anything they will need to find out that the CPE is emitting or doing.

I guess if you’re truly concerned you shouldn’t have WiFi at home or a mobile phone. Too bad 5G signals have similar capabilities, but at least the signals don’t propagate as well.