The only real reason is in terms of where they are. They are heroes who save mankind, so in the eyes of ordinary people, they are extraordinary and do not exist among ordinary people, which is why there are the words "super" and "chivalrous" to describe the ordinary people's perception of them.

So, the real heroes may be unknown in normal times, but when they really encounter a crisis, they will come forward, which is also the ancient Chinese saying, "the great hidden in the city".