The core issue here is not whether or not the Avengers and superheroes in general should be held accountable to regular society, its whether or not society can even hold them accountable in the first place. Yeah you can jail the ones that are just regular humans but how do you control the hulk or thor or wanda or strange or captain marvel who all have powers that logically could make them virtually unstoppable against conventional forces. As others mentioned elsewhere in the thread, the Security Council responded to the Chitauri with a nuke. If the Avengers weren't able to control the Hulk, how many cities would the UN or US have nuked in order to try and stop him?
The fact of the matter is, and was always the case even in the comics, is that the Pro-Accords/Register/Ironman side only had as much power as the super humans who decided to align with them did. Without them, regular non-powered society would've likely wiped itself out trying to kill some of the world-level threats that exist out in the meta human community.
The funny thing about cape comics is that they tend to portray the larger earth-based community of metahumans as never truly being above the human society. The major place this diverges is with the X-men/mutant storylines, where you'll have groups of mutants who are definitively trying to create a society of homo-superior. Past that though, its mostly what I described earlier. It's almost naive by nature, because it presumes that the vast majority of metahumans would effectively have goals and desires that rarely aim for society ruled by homo-superior/metahuman. Yeah you get the villain or three that want to take over the world, but few that frame their desires towards the metahuman community in the same way Magneto desires for a mutant-world earth. And while this would make more narrative sense in an isolated story, DC and Marvel literally have hundreds of named metahumans respectively, and for some subgroups like mutants, the number of possible metahumans in-universe clearly go into the millions, which is why big crossover events like Civil War can fall flat under interrogation.
If this was real life, I would absolutely hope and pray there is an Avengers-like group who are atypically and unambiguously good natured as Captain America to rein in the Hulk/Sentry/Wanda/Namor types. And as much as *eye* would like to think that regular society could hold a Thor or Hulk accountable, it would be straight up hubris.
How many hypothetically evil Hulks would need to appear in our reality before we nuked ourselves out of existence trying to kill them? 1? a Half-hulk? Come on. In reality, you better hope there are superheroes that are decent and human to protect us regular folk from the ones who aint. You can't put no leash on that. Like at that point, we're not in a position to be making demands, regular humanity wouldn't be at the top of the food chain.
