No they wouldn't. The police are paid to check those things out, not to make facile assumptions. When they are the license plate they would have noticed that the person they saw in the video was not the registered owner of the car. That was absolutely something worth following up, which was why the author's mother found a police car waiting for her when she returned from dropping her daughter off at the airport.

The probability of a crime occurring is not the only factor that has to be taken into account here. There's also the severity of the possible criminal outcome. Kidnapping is actually relatively common in the US by international standards, and it is among the most aggressively prosecuted crimes. Until 1972, kidnapping was a capital crime, ie you could get the death sentence for it.