Strictly speaking that question was for the author. Less strictly for anyone who wants to demand the resources of contributors, even if contributing themselves. The question is about balance and consideration, recognizing that even if someone is giving away their work they live in a financialized world that doesn't respond to their generosity by giving them free access to resources (most of the time).

The distributive justice matters you reference are big problems. To answer your question: we can because they don't actually have all the power, we just don't find the will and not entirely without reason. If we used taxes to extract those funds they would likely be priced in so that the population is left funding them still. It would risk a privileging as suggested by a peer statement and the real solution has to be pretty systemic.

The problem is broad and something like we live in a society where the most privileged amongst us are happy to have a smaller pie so long as they get a larger proportion of it. Even if it's caused by ignorance, that doesn't keep it from being the case. It's also true that we have societal behaviors which reduce our productivity due to the injustice of things. We punish the sincere and well-behaved for the benefit of those creating asymmetric information and abusing others.

I don't think we should be surprised that this leads to bad results and things functioning less capably than they could.