Just one of the reasons places like NYC aren't losing their minds over the courts blocking Stop & Frisk - because the frisking is now a no-hands-needed exercise.
A few years ago at the WWII Memorial Barry-cade of work, that has since become known simply as the "Return to Sender" event, a few of us discussed the tech in play surrounding several FedGov spots.
Now it is mainstream.
Here's the link.
Don't be scared of their tech - but you'd better respect it.