Extortion in the tax free shops in Thailand

Airport authorities in Thailand checks passengers from the 1 June 2007 for carry-on items with liquid contents such as gel and sprays after the liquid ban took effect yesterday. Passengers are prohibited from carrying on board liquids, except for baby milk and medications, exceeding 100 millilitres. The ban come as a shock to most Thai passengers since the TAT not told anybody. The tourist are used to this kind of behaviour from abroad.

The worst thing I saw when I travel was the tax free shops offering a plastic bag if you bought good valued over 2000 THB. You need that plastic bag otherwise you can not board the plane.
When will they learn?