The hero is called in to patch up some flaming wreckage. Mgmt never allocates the resources to actually fix the root cause. Thus the hero is seldom at fault, otherwise they would be Jane Doe. There is a specific type of hero who deliberately creates this situation, but IME they are not the rule.
Source: I was That Guy for about 8 years at three different gigs. Now I specifically negotiate no afterhours support in my job interviews, and turn off my phone when on holiday.