I'm not suggesting in the least police start randomly stopping people walking down the sidewalk, going door-to-door, or anything like that. If in the course of your normal business in public you have reason to need identification to do something, we should make the requirement that it be a Real ID. If a state wants to issue non-Real ID to illegals and let them drive in that state, more power to them. They can do that. If a state doesn't want to play along, the federal government should withhold funding in general because that state is really shielding criminals and should be made to enforce the laws like everybody else is doing.
Imagine this: A state starts refusing to respond to bank robberies. The state claims that's a federal responsibility and they want no part in that. That is EXACTLY what a sanctuary city, state, whatever, is doing. It is selectively enforcing laws and ignoring those it doesn't like. We shouldn't put up with anyone or government entity refusing to enforce the laws as written.
So, while immigration is a federal responsibility, like bank robbery, state and local government should be helping to enforce those laws and one way to do that is when in the course of normal business they have reason to suspect someone is here illegally, they have a duty to try and determine whether that is the case or not and assist the federal government in the arrest of such persons for the crime(s) they've committed.