With call display, most people these days don't even bother answering phone calls which don't identify the caller, and no one trusts anonymous phone calls.

When you cross people on the street, you identify the people you know, and those you don't know, and can say, "I saw X in Walmart yesterday." If something happens, police ask for eyewitnesses who can identify the people involved.

When you see someone wearing a niqab, you have no idea who that is, and whether that is the same person you saw elsewhere the day before.

Amazing that we are now in a position where this has to actually be spelled out.