Art is right, Doug.

It's small consolation if you're eventually cleared, if you've been detained and possibly jailed and you have to pay for an attorney, etc., and you've maybe lost business or a job or important non-business events while you were "processed" after being taken into custody because you weren't carrying your green card or passport or birth certificate.

I can see it now: A mariachi band en route to a Cinco De Mayo gig is stopped by the Arizona cops and asked for their passports or birth certificates. Since they don't normally carry these around -- being US citizens and all -- they are detained, miss the gig(s) and lose not just a few hours' or a day's income but possibly a longer-term client for being a no-show.   

There will no doubt be many other similar situations if this law is allowed to take effect.

Being stopped by the police can be a major disruption to your schedule, even if you are not charged with anything.

Anyway, if I lose or forget my driver license and am stopped by the police, I may be given a citation (after the cop calls in to check who the car is registered to, etc.) but I will not be arrested on a criminal charge or taken to jail. I'll probably get off with a slap on the wrist if I can produce my driver license within 24 hours.      It is not the same kind of offense as driving when you aren't licensed to drive.