If it was just to verify they were legal in the U.S. the poor people should not have to carry around their paperwork. I think is to force them to have to carry their paperwork and demean any form immigration in the state of Arizona. It is not right and should be looked down on to make them feel that have to have papers or get deported.
We have laws in place not only to protect migrants but also to protect current citizens. By making someone carry papers at all times you increase the opportunity for them to be regnized as legal or illegal. If I knew that I could not get away with being in a country because the require me to carry papers that I will be asked for on a regular basis then I would work towered doing it the legal way.