anyone can in theory be driving a car. is it my wife, or me, or my kid taking the station wagon out this weekend?
it's also why red light cameras and speed camera send tickets to the registered owner, not necessarily who is driving. my sister in law borrows the car and I get the ticket
In the broader context PII is a looser concept, and can be thought of like browser fingerprinting. The legal system hasn't formalized it nearly to the same degree, but does have the concept of how enough otherwise public information sufficiently correlated can break into the realm of privacy violations. I. The browser fingerprinting world that's thought of pretty explicitly in terms of contributions of bits of entropy, but the legal system has pushed back on massive public surveillance when it steps into the realm of stalking or a firm of investigation that should require a warrant.