The British actor Julian Sands went missing some days ago while hiking near Los Angeles. This snippet from a recent news update caught my attention (emphasis mine):
The San Bernardino County Sheriff’s Office announced Wednesday that the search will continue “by air only” using RECCO technology, which can detect “reflective material, electronics and, in some cases, credit cards.”
About RECCO technology: https://en.wikipedia.org/wiki/RECCO
So, if someone wants to escape detection, they need to totally empty their pockets!
(Although I’m glad if RECCO helps find people in an emergency.)