What about the crime of entering the US illegally? OR the crime of welfare fraud, filling forms out under a fictitious or stolen SSN?
You cannot tell whether someone is an illegal by appearance any more than you can tell whether someone is illegally carrying a concealed weapon. We should not live in a world in which we have to prove we’re not a criminal to every cop we see.
However, when one commits a crime, they get frisked. It’s logical to inquire about immigration status at this time, also.
It’s only a matter of time before the criminal element is deported, and with the loss of driving privileges to illegals, some of the incentive of staying is lost.