My guess, yes, this is just a guess, is that they do not have the high-volume, high-speed CTX scanners at DMK like they do at BKK, and that they have been a bit lax with security measures in the past. And given recent incidents and focus/attention, these new security measures are necessary.
Quote:
http://englishnews.thaipbs.or.th/tig...-at-don-mueang
Airport source said this measure is not new but is not strictly enforced in the past.
Under this regulation, all bags taken into the check-in areas must be first X-rayed.
Typical lack of planning, getting caught out and then trying to recover. Welcome to Thailand.
http://bangkok.coconuts.co/2015/07/2...urity-measures
http://thainews.prd.go.th/CenterWeb/...C5807200010034