This is a pretty bad analogy, because there's very little that online advertisers track that license plate readers can't. In both cases, it rarely stretches bey

This is a pretty bad analogy, because there's very little that online advertisers track that license plate readers can't. In both cases, it rarely stretches beyond a dataset of "Which people have visited which (pages|businesses)" and whatever statistical inferences you can claim to make from that data. Businesses already use license plate readers for marketing and analytics purposes. (Although, of course, not as widely deployed or as well-known as advertising cookie tracking)