“Seriously, if a cop asked you today to prove you’re a citizen, what document would you show to convince him?”
The cop’s going to run your license number before he gets out of his car. He’s going to know your name, your age, any previous violations, your home address, if you have a concealed carry permit, any outstanding warrants, if you are insured etc.
I'm not at all sure that this is an accurate statement of the new law.
a) The officer has to have "reasonable suspicion" (actually a technical legal term) that you are not a citizen to even quiz you
b) Of course, he could have that, and simply be wrong;
c) As I understand it, he can quiz you, and if he THEN has "probable case" (another technical term) to think you are illegal, he could arrest you, but "producing proof of citizenship" isn't part of it.
If you are a citizen, you can probably convince him by talking and answering questions. And, of course, you may be a non-citizen, but be legal (greencard, visitor visa, etc.).
But, it does raise the question of, in your example, how does the license info show that you are a citizen? -- an illegal might have a license, or be driving someone else's car with permission; or, the person might have a bad record, but still be a citizen?
How should a citizen react if a cop treats him with "reasonable suspicion" or says he does? what proof can you offer, or argue?
If this is the case then the cop won’t have to ask any questions.
In your example an illegal could have all that. I’ve read about people getting busted here in Houston who’ve been here for 12 years and own homes. Still illegal.
Now, per your example, what about the citizen who doesn’t own a home, no insurance, etc. Plus he’s Hispanic. I still hear BORN IN EAST L.A. by Cheech Marin.