Duress fingerprints. 'nuff said.

Or a configurable timeout, rather than the apparently hard-coded 48 hours.

Or ask for a PIN if the phone's radio detects many more other radios in the vicinity than a few minutes ago ("Because you might be under duress, please enter a PIN now.")

Or if a phone has been sitting on a flat surface for a while, require a PIN.

Or require a PIN if the phone is tapped with a duress code ("Shave-and-a-hair-cut"). Could be pretty subtle.

Countermeasures like this are useful both against thieves (who might want to unlock your phone and get access to your accounts) as well as against state actors (ditto).