[ohgr]

Many layers of physical controls and regular audits mostly.

[lmm]

What does a physical control mean in this context? Like, disabling that part of the phone's touchscreen?

[ThePowerOfFuet]

Think personal devices not being permitted beyond the entrance of the building, stored in a Faraday box.

[Alupis]

So in other words... nothing stopped anyone from doing this either. Except the fear of potential punishment.

[HWR_14]

I'm not sure how you ignored the "many layers of physical controls" part of the comment.