Does the ground crew check whether there is a life jacket under every seat before each flight?
In my experience,No the ground crews do not check before each flight.They check at night while the aircraft is undergoing RON (required overnight maintenance).The life jackets are very expensive item and if your friend had been caught he would have been in serious trouble.People like him are the reason air travel is so expensive.There is a red strap that holds the life jacket in its pouch and if removed hangs down making it more noticeable.The life jackets also have a shelf life…meaning that they are only good for a certain period of time before they have to be overhauled.