Disguising the face in public has been the subject of attention in times past, from veils to ceremonial masks, and including the helmets worn for protection in hand-to-hand combat by warriors -- or the balaclava masks worn by special forces (and terrorists). In modern society it tends to be only those driving potentially dangerous vehicles that use such devices, as is the case with motor cycle riders. But high tech cops also make use of the silvered variety, partially to intimidate. In many cultures, veils are still worn -- usually by women (as in Islamic cultures) but in some cases by men (Touaregs).
Claim:
For those exposed to the press as witnesses, or accused in a trial in which they may be proven innocent, the same challenge exists. And not to be forgotten are the shy, or those with facial disfigurements which attract unwelcome comment. In some contexts, this may simply be people of different ethnic groups. And with the increase in electronic surveillance in public places, many may want ways to move around in public with a sense of privacy. But aside from these examples, those who claim real need do not have access to any suitable device, other than chic dark glasses. Prisoners may have a blanket thrown over their head by the police, which is rather primitive and undignified for the 1990s.