Seems you are alone in this thread and to be fair, I'm gonna help you out
This is what deuce is worried about....
And its idiotic for him to be worried about that.
You need reasonable suspicion to be able to be asked for proof of citizenship.
Simply going down the street on a bicycle isn't reasonable suspicion.
Generally this will occur upon finding out information during the investigation of another potential crime, such as speeding. At which point, if there's reasonable suspision to believe another crime is being commited, IE entering the country illegally, an officer may further investigate. If there's evidence to suggest that the crime was commited you can be arrested while further investigation happens.
If I'm pulled over for a traffic stop because I'm speeding, that's fine. If then in that traffic stop they smell marijuana and notice rolling papers on the seat they can search my car. If they find marijuana then they can arrest me and I'll have a chance to defend myself in court.
If you're pulled over for a traffic stop because you're speeding, that's fine. If then in that traffic stop you can't provide a legal drivers license the officer can ask for proof of citizenship. If you can't provide that then they can arrest you and you'll have a chance to defend yourself in court.
In the first case if somehow the individual had a lisense for medical marijuana but didn't have it on him at the time, he could produce it later for the court and attempt to get off that way.
Likewise, in the second case, if the individual did have proof of citizenship and simply failed to have it with him at the time, he could produce it later for the court and attempt to get off that way.
Being in this country illegally is a crime. Having probable cause to believe you've commited that crime warrants detention. The ability to investigate to find that probable cause is reasonable suspicion.
The law is known, its not hidden, its not secret. If you don't carry identification of some kind on you in Arizona expect there to be potentially a problem and an inconvience if you're breaking the law and get caught because you may be asked for it. That's the risk you take in not having it on you. However if you're honestly a citizen here all it will amount to is an inconvience as you'll be able to show and prove soon enough, or more they'll be unable to prove, that you're a U.S. citizen once you are able to produce the paperwork.