"I wonder why this has not been developed by the military / government."

They actually outlined this in the article. The reason pretty much boils down to the fact that gear specifically for the military has to adhere to whatever crazy shit the higher ups demand. This makes developing a proof of concept/ fully functioning, marketable device rather difficult as the costs begin to skyrocket.

These guys took the opposite route: develop the tech, bring it to market, then let the military get in on it if they like it.