Throughout the decades, interplanetary attacks and alien invasions have become a regular occurrence on earth. No one was shocked when a village or so would be reported in the news, wiped out with little to no survivors. Alien invasions could be stopped, of course, but that didn't mean there weren't any consequences. Sometimes, entire villages would be deleted, and there's nothing the superhero agencies could do about it.
After all, superheroes aren't omnipotent or gods, and it's normal for them to be helpless in specific scenarios. Of course, there will always be hate when it comes to heroes with subpar results, but that would more or less be overlooked, given the overall success rate of superheroes when it comes to fending off invasions.