[AppyPappy]

For one thing, the police would be able to find out of the guy had any prior convictions for domestic assault or other crimes. Or they could find out if he was a wanted criminal.

How many stories have we seen where the cops let a guy go and we found out later he was a wanted criminal? Then everyone blames the cops.

[Old Professer]

Most criminals aren't convicted on the basis of a piece of paper found on their person; not everyone who is obdurant is a high criminal.

[Outlaw76]

"For one thing, the police would be able to find out of the guy had any prior convictions for domestic assault or other crimes. Or they could find out if he was a wanted criminal. "

I'm sorry, but I find that to be a very week reason for demanding his ID in an uncivil and arrogant manner. Again, he could have gotten the information with a much more civilized approach. Your line of reasoning in this is just as valid as allowing the officer to shoot him and find out who he was afterwords, you know, just in case he was an axe murderer or something.

[eno_]

How many stories have we seen where the cops let a guy go and we found out later he was a wanted criminal? Then everyone blames the cops.

That's only because it is less well known that the cops put their morning box of donuts on top of the huge pile of default warrants sitting on the desk down at the PD. It doesn't take a sloppy traffic stop to catch a cop slacking off on catching genuine bad guys.