The villains appear after the fact.

Spider-man, the Batman all the rest fight crime because (generic) crime is the problem. As with James Bond and SPECTER (SPECTRE?), there's a point when the USSR and the cold war was too complicated to be an easy-to-punch baddie, even with the gulags and tanking, so James Bond got a Moriarty, a nemesis to fight instead. The superhero rogues galleries are what happens once it becomes awkward that all the superhero does, is as Garth Ennis put it beat up poor people. And so Jokers and Doc Ocs and Red Skulls are invented when the real Nazis are no longer a threat.

When we stick superheroes into the modern western world, the pretense is that the system mostly works, essentially that Ronald Reagan isn't around gutting social programs, turning prisons into (pretty literal) gulags, fueling the war on drugs and otherwise making the federal and state justice systems into even more of a system of oppression than they were after prohibition (specifically to target non-whites, at that). In the DC and Marvel worlds, police are not overly brutal. Prisons are not overwhelmingly unhumanitarian (nor are they impacted). And yes, criminals really did make some avoidable bad life choices (rather than IRL getting steered into the school-to-prison pipeline).

Though the silver age, the system ran by magic capitalism, even as IRL industries were capturing the regulatory agencies that were supposed to prevent them from driving precarity and poverty to 80%+ of the nation (and thereby fueling the white Christian nationalist movement that is taking over the federal government and many states today).

Through the dark age (that is 1985-1995-ish), Batman sometimes killed, but Frank Miller noted that the thugs were so awful that they deserved it. The criminal element were painted as literal undesirables you could do anything to without moral concern. Sure, Arkham Asylum was a literal dungeon and the jails were infested with rats, lice and scabies (as they are IRL) but it was okay not to give half a fuck about the inmates, because we know what they did.

And yes, even when the current MCU villains have a point, they are obligated to offer a solution that involves decimating the public, so that they can be waved away as too radical, and the Avengers can go back to serving the establishment plutocracy (and not the public). Heck, even Adrian Veidt (Ozymandias in Watchmen ) killed half of New York in order to stop a nuclear holocaust.