No phones allowed anywhere near a meeting, no watches, no electronics or metal of any kind.
No jackets, no hats, and make it a rule to turn pockets inside out, and lift shirts, everyone in the meeting has to do it, even Capos and hire ups.
That's the only way it work.
Maybe during induction ceremony - everyone has to wear tank top and gym shorts. I know how it looks, but it keeps the risk of recording down.
In this day and age of cameras everywhere, recording devices everywhere, GPS, etc, they need to come up with super strict rules.