...and their bags were left behind because no-one did the checks, tagged the bag & sent it down the belt....
Would it surprise you to hear,
Buster, that self check-in of pax AND their baggage is already a
fait accompli at a couple of airports in Japan.
The required number of baggage tags are issued, via the "hole in the wall", along with the boarding pass (where the pax is also able to nominate exactly which seat he wants - and gets, if still available). Said pax then tags bag(s) and places them on a belt, which weighs them and transports them "down below" via an x-ray security scanner.
Dunno what happens if they are found to be suspect - I guess s/he would get a call over the airport public address system, to report somewhere to open the offending merchandise.
So be careful p!ssing the pax off, girls and boys - the more complaints you stir up, the more ammunition you're giving your employers to use against YOU.