At times, the term 'Military or LEO over-runs' can be a convenient marketing gimmick... FEG you sound alittle cynical, it was the 'Uzbekistan Army' of course!...
Sometimes Companies will approach a 'Military' (US, or whoever impresses) and offer a trial, or test of a new gun with some 'new whizz-bang' to get feedback and hopefully an order.... Or it can be a Governement Agency requesting a 'test-run' of a new concept for a future order... etc, etc, etc.
In the case of the FNP-9, if the 'sale' gun is identical to the normal, stock retail FNP-9, then you're guess is as good as mine... ie. 'marketing gimmick'.... But I'll ditto rellascout five-times when he said "Who cares at $379 the gun is a steal"... He's dead on... the FNP-9 is a super gun at under $400!!
'And the beat goes on'!