From personal experience, close by people are far more likely to hack you than strangers. Systems should reflect this. For instance, WhatsApp Web shows a prominent notification. Signal does not. So one investigative technique is to get someone's phone for a minute, connect Signal to the desktop client, then rather silently have access to their account.

When it comes to unlocking phones, I'm far more worried about family, romantic partners, friends' kids playing pranks or trying to get a bit of cash than I am about some organized crime gang or CBP faking my face or fingerprint.

I personally wouldn't want even my close family members to have complete (read AND write!) access to my texts, emails, Facebook, etc. even though they don't pose a "genuine malicious threat", and I'd guess that's a fairly common sentiment. Privacy has merits beyond security ramifications.

I think parents who have had their kids purchase things from the app store without their approval might disagree.