Crew coaches going through the security point? Now that IS a real security risk. You hide something lethal on the coach, they don't find it in their search and you pick it up 5 minutes later. This must be the easiest way for crew to get illegal items aboard an aircraft. Amazingly, the DoT regard this risk as acceptable.
Once I accidentally left my mobile phone on the seat and it was still there when I returned. So much for a thorough searching.
The only solution is to have a different coach airside.