The scenario described above? Chock full of LEGAL reasonable cause. That isn't what YOU are advocating.
So, let's be clear, Partisan. You are in favor of the police walking up to people on the street, stopping them for zero reason, and demanding ID. If no ID is proffered, they get hauled off to jail with ZERO SUSPICION OF CRIMINAL ACTIVITY and held until they prove that they're a citizen. And that seems legal to you and how the police should be doing business?