I totally agree that the FSM checking the crew's cabin secure check can look very unprofessional. I was recently travelling as a pax on a VS flight and noticed the FSM checking the cabin was secure for take off. On noticing a pax had put a blanket back over their knees she yelled (in the style of Rickaaaay!) Debbie! Poor Debbie came rushing up to have the offending blanket pointed out to her and berated right in front of all the pax. Whilst I accept that this FSM probably isn't represenative of most VS FSM's, it looked so awful and everyone really felt for the crew menmber in question.
I too don't know of any other airline that do not trust their crew to carry out cabin secure correctly. Surely this is what they are trained to do??