We have traffic checks often. Checking for licenses, registration and insurance. I think the probable cause, is thay someone may not be legally driving, just like checking to see if someone is legally carrying.
They probably would check the pedophile, if someone called them about it.
I think maybe the suspicion was the original call.
I imagine he did say something like...’may I see some ID?’
A driver’s license is a privilege. When you apply for one, you agree to certain things, including stopping when a cop attempts to detain you and showing him your proof of insurance and your actual license when requested. It’s not the same thing as walking down the street minding your own business or eating breakfast in a coffee shop with a group of people. There’s no pre-established, signed consent to do a damn thing a cop asks you to do.