You make this sound easy but look at how that worked for NSLs. They got a ton of pushback for that and there’s no way to keep that a secret for very long – especially since things either end up in court or involve foreign governments who won’t share the desire to keep things secret.
On some level the US could also pass a law that says every iPhone user will be summarily executed. That’s how sovereignty works. Is it a realistic concern? Probably not.