People with barely expired plates are normies who made a mistake. Safe. People with temps expired a year ago aren't making a mistake, they're willfully and openly displaying defiance of the law. That makes them scarier.

In some places where I’ve lived, local LE mounts ALPR systems atop most of their fleet. Those read “formal” plates as vehicles pass near the cruiser, and they proactively alert against a watchlist. Which presumably somebody’s hooked up to periodically ingest lists of recent lapses alongside the usual stolen/wanted/pile-of-unpaid-tickets sorts of stuff.

My sense is that such systems are rather less consistent at reading temp tags, and that temp tag issuance tends to be decentralized/dealer-based, rather more ad hoc, and thus rather less legible for semi-automated enforcement purposes.