I like to think about how this works at smaller scales. When there is an office full of people all being paid about the same and (critically) where they all want and care about the same outcome, the shit jobs will get done. I have often called myself a "code janitor" since I clean up shit that was left behind. It's not because I didn't want to be working on fun greenfield projects but because it was shit that just needed to get done. So I did it. And so did others.

Another example to play around with is when you go camping with friends. There's some shit work that just needs to be done. People pitch in. The same with staying at a friends house or a vacation rental with friends. Or cleaning leaves off of the storm drains. We all do this sort of work because it makes our lives better. If literal shit was piling up in front of my house I would probably shovel it even if it took 8 hours.

Natural disasters are also examples where people do work for free without expectation of compensation. I think people are more like that than what happens in apocalyptic novels (even though I love reading them).