"Surely the best helicopter to look for "vulnerable" persons is the Air Ambulance?"
DUH........Exactly how many Air ambulances are fitted with cameras?
If you did fit them with cameras, what would you remove to maintain payload, ...the oxygen bottles? Maybe the paramedic?
Exactly how many air ambulances are publicly-owned, and therefore potentially taskable?
What will the air ambulance do when it finds someone who might or might not be the missing person walking on a remote beach at 2 am?
Maybe we need to fit the air ambulance with police radios as well as a camera?
Come to think of it, we could paint the air ambulance blue & yellow, and write "police" on the side whilst we are at it.