Someone I knew involved in defense procurement explained the proliferation of such devices. Basically these small companies who make these things will hound politicians saying they've got a device that can save soldiers/police lives but your bureaucrats who handle supply chain sourcing and testing are slowing us down - please help us accelerate this and we can save lives. They'll usually bring up that this is a small company who is competing with the military industrial complex keeping them out of the game. This usually results in one or multiple politicians pressuring the applicable agency, to the point where they'll threaten to withhold funding to consider a trial or small purchase. Fast forward a year and these devices are deployed and thrown away due to the fact they obviously don't work. It's worse in the law enforcement circles where they actually believe the stuff until a court gets involved and things get thrown out and guidance is given to drop the crap.