Back in the 90’s, when AZ made E-Verify mandatory, I became the “Authorized E-Verify Officer”.
As I recall you couldn’t verify someone until they were hired. If they came back “dirty” then they had a month to file an appeal. You pretty much couldn’t fire them until the appeal process worked it’s way through the system. (Even though AZ is an “at will” state.)
You could not check existing employees. And all your hiring records could be inspected at any time. (Though they never were.)
About the only advantage to the employer was you weren’t liable for anyone that had been run through E-Verify being an illegal.
Maybe when Lake is elected governor she’ll make a few adjustments and fix that BS.