That doesn't make any sense... How does having one screwed up system justify another? Maybe we should start paying twice for groceries too, because we pay twice for toll roads and research papers...
My point is, whether or not you pay a fair amount doesn't depend on how many times you pay. Let's say your fair share is $10; $3 goes via taxes and $7 via the other mechanism. Here's a couple of scenarios where it's a good choice:
1) The new road is 60% in the public interest and 40% in the interest of its users, so 60% is paid with taxes and 40% via tolls.
2) Society feels it's reasonable that all children, regardless of family income, should have educational resources. 90% of school is funded by taxes and 10% funded by fees paid by students' families (lunch, field trips, books, etc.).
Both of these are reasonable, as long as the payment is actually covering costs - but in this case the first payment covers some of the costs, and the second payment increases the cost. That is, as a taxpayer I'm paying 1) for the research and also 2) for the extortionate access fees for universities, and as an independent researcher I'm ALSO paying 3) for my own private access to the results. The problem is that the funds from 2 and 3 do not fund the research, they fund the parasites that make 1 more expensive. I have no problem with a two-part payment for things where private benefit and public interest have the relation you describe, but when the secondary payment is a) entirely unnecessary, because the entirety of the work done is funded by the first, and b) feeds disgusting evil parasites that do nothing but harm to society, it's clearly immoral.
> The problem is that the funds from 2 and 3 do not fund the research, they fund the parasites that make 1 more expensive
Speaking generally, paying for someone else's profit is essential to the free market. Without profit, much less would get done.
Speaking about this case in particular, knowledge, at least much of scientific knowledge, should not be sold at whatever prices the market will bear, which is what these publications seem to be moving toward. Imagine the prices you could demand for knowledge of immunizations, relativity, DNA, law, history, etc. (if they weren't already publicly available). Imagine the disruption to science, to the advance of knowledge, and the incredible cost to humanity if only a few with enough money could access these ideas.
1) The new road is 60% in the public interest and 40% in the interest of its users, so 60% is paid with taxes and 40% via tolls.
2) Society feels it's reasonable that all children, regardless of family income, should have educational resources. 90% of school is funded by taxes and 10% funded by fees paid by students' families (lunch, field trips, books, etc.).