I think the greatest concern is that the cops don't seem to care about personal privacy at all. They'll do anything that's physically possible to do to prove guilt of a person, they have the Power of The State behind them. They're going to get access to this technology and they will use it to stop vehicles, it's simply a matter of time. Police in the US only ever get more powerful, more militaristic, more immune to consequences. There's an easily visible path from where we were before the bill to where the poster (incorrectly) claims we're at. Just because they don't currently have the power doesn't mean we should be taking every affordable step towards giving it to them.