Earlier quoted context omitted.
You understanding is mistaken. Graeber's "everyday communism" is not a market, and his whole larger point is that contorting everything to the lens of markets is simply ahistorical and unempirical. I'd strongly suggest reading his books. They profoundly changed my understanding of how human institutions and society form.
Unless it's some sort of complete post-scarcity, it has to be understandable in market terms. What happens if people try to free-ride on the whole "communist" system? If they get excluded from its benefits, that's equivalent to enforcing some bundle of property rights.
I like economics and math too, but the whole discussion of markets is a terrible starting place for deriving results in ethics/psychology. If you insist though, notice that unions will happen unless some other organization is working to prevent them. What do you suppose this means? People are aligned with each other exactly because they've noticed their coworkers are not corporations or governments.
Although the two are entangled, politics is a more relevant framing than economics here. If people weren't broadly aligned on basic stuff, then autocrats, theocrats, kleptocrats and so on would simply not be interested in dismantling democracies. They make that effort because they must.