Any good deed would have to be performed flawlessly every single time. The media would be on their ass over even the slightest mistake. People question why the Superman isn’t doing MORE (because we are never satisfied with anything). Why didn’t they do more or prevent bad stuff from happening earlier? Why is Superman helping ABC but not XYZ? Why is Superman only helping XYZ but not ABC? What’s Superman’s connection to the government of the nation it resides in? What happens if that country goes to war? Will the supervening intervene? Your country of origin may tolerate it you but there’s no chance foreign nations would ever accept such a thing. What happens when you intervene in a country that doesn’t want you there? The mere existence of a Superman would cause a massive shift in the global power structure and force everybody to completely change how everything worked. At the very least it’ll kick start an industry that’s solely focused on how to shut you down as quickly as possible if and when they deem it necessary to do so.