It was not that long ago that few people wore them!
My teachers at school never wore them, but I think all their successors now do.
The Ministry of Defence establishments near my home used to insisted each member of staff (including some of my friends and relatives, hence my knowing) wore his or her name-tag openly within work but conceal them out in public, because it was thought an immediate identifier of employer. These days so may people from so many institutions wear labels on strings round their necks hardly anyone would notice an MoD employee in the crowd.
