Not only have modern "militarized"* cops taken to hiding their faces in public...
Some of them - and this has to be a department-level thing - have taken to detaining people without official record, and refusing to give names and badge numbers.
Guys? There's a reason the traditional police uniform has the officer's name on it, and the badge has a number. Turn the cop into an anonymous cog in the machine, and you lose all accountability. And the angry public has no way of knowing which cop was the bad cop. This way lies all-out urban warfare.
And the paperwork is there for everyone's protection. Lose that, and suddenly there's the potential for "losing" detainees who were never officially detained. (There's enough danger of losing those who were officially arrested, without adding zero-paperwork cases.) This starts to sound like bad times in Russia or some Third World hellhole.
* Scare quotes because the military equipment is not accompanied by the corresponding training and ROE, nor the attitude.