Airport security is,
AFAIK, the responsibility of the airport operator, obviously working to standards set down nationally, or even internationally.
Pax not knowing that they need to remove coats, laptops from cases, liquis in plastic bags, belts, coins, anything metallic, etc., will obviously slowd things down. Not every pax is a frequent flyer. Not all staff will have the required patience all the time.
Could a separate lane for "regulars" (other than for "fast track" cardholders) be a good idea?