Agreed, Surely Not. It is always the application of control, as with the correct boarding sequence. Happily, the low cost of CCTV makes the monitoring of pax checks simple. If there is a record of the pax being stopped and questioned, it would go a long way to stop the complaints. The emergency services staff who wear body cams have found them very helpful in this regard.
The suggestion of a breathalyser is VERY good.