Actual human traffickers and whoever not are onto this, and take steps to evade cameras. Even if they aren't this is a very poor strategy. If you have a suspicion about someone, the stupidest thing you can do is pull them over. That risks blowing the whole investigation. That particular vehicle and driver may have nothing incriminating on them, and will now tip off their entire network.

Imagine how powerful the human trafficking group with a couple cops on their payroll would be.

Basically like pulling up a menu of possible victims and tracking their location down to the minute.