in some middle eastern countries mail works in a bit different way.
when package arrives, normally you have to pick it up at a post office and there normally officers ask you what is it. they have the right to open it in front of you. and believe me they are present and have heard of concentrates.
the package can be simply taken for a random routine lab tests.
in some countries, and i lived in so many in the middle east, one can even get randomly a piss test and if tested positive thats minimum of 4 years.
so i guess it is all a matter of prospective. pragmatism is one thing, but human factor also makes a difference.