Not many other nations are developing this technology. Now, this could be because the US military is far superior to those of the rest of the world. Or it could be that the 1995 Protocol on Blinding Laser Weapons banned lasers and the US military just couldn't give a fuck about international weapons bans.
The ban came after concern from humanitarian groups, something about potential crowds of blinded refugees wandering around in a war zone and slowly starving to death. So the PHASR developers just turned own the power enough to skirt the ban.
The problem is that they still had to make it powerful enough that even the biggest badass enemy soldier would still go running the opposite direction, screaming and clutching his eyeballs, but that it somehow wouldn't do any damage to an innocent toddler's still-developing retinas. Seems like kind of a fine line there, but we're sure they know what they're doing.