A popular tactic of intelligence agencies, Mata Hari passim.
I travel into the US constantly, as do many people I know, and I have never in person come across a single person this has happened to.
Not saying it doesn't happen, just that it's easy to blow this stuff out of proportion.
That's what I'm trying to do here - offer the view of someone who does this every few months for nearly two decades.
Cute girl offers glass of champagne and complimentary strawberry 'so.. I'm gonna need you to unlock your phone, give me the password to your work-related e-mail, your personal e-mail and all your social media accounts.'