But a police officer can stop your car _right now_ if your passenger-side taillight is broken and then search your vehicle for a variety of things. So many marijuana related arrests have happened exactly this way. With license plate scanners and chips being embedded into cars, the ability to be pervasively tracked in a car is more apparent than ever. In contrast, walking or biking doesn't require registration or licensing by the government.

(As silly as I thought the movie was, the protagonist of the first Jack Reacher movie took the bus everywhere specifically so the government had no records on him, so the idea certainly isn't lost in popular culture either.)