It actually does apply to other situations (e.g. barber), but since for the most part, despite it technically being muttar, the poskim frown upon it, it’s kind of reserved for cases of need. A haircut is just not that important.
Handshaking is a different story. The poskim who asser, according to my understanding, hold that it is inherently derech chibah so ???? ??????? doesnt apply.