Not at all. I'm not pointing to any 'conspiracy' , as such, at all. I suppose if there was one, the journals themselves would be doing that, since they get money for publishing.
And no - not everything done with public money hits PubMed or any other db as a full article. Not by a long shot.
I'm saying that money gets re-routed along the way, usually in a top-down fashion. At the end of the road, we likely paid for the work with our tax dollars. The money does not generally all get used up by the agency which got the money to start with. They will make grants out to other sub-agencies, and from there on to university programs or NFP groups (which often maintain close ties to the original agencies in one or more fashions for the purpose of getting and keeping those grant dollars rolling in). At that point, we have already removed (they seem to think) the public domain rights from the work and its results, because they are not government employees, themselves. You may, or more likely, won't, recognize the authors or some of the institutions named in the abstracts that get listed. And because of that, you nor I can even begin to calc how much of it we actually do own. In that sense, it's not unlike interlocking directorships in the corporate worlds...and actually, downright identical, in many ways. Nothing in that mere abstract is ever required to reveal those relationships to you - but I assure you, many, many exist.
Here's an example: An M.D. heads a large association of M.D.s which is in large part funded by memberships, but also by the insurance industry, which does not enjoy suits over environmental injuries, as we already know. The same guy heads the related department at a public university. He and a couple of others in his group wangle seats on government advisory committees. The agency they are at gets its own budget, and not only determines what the study agenda will be, but who gets the grants to perform those studies. Clearly, environmental injuries are going to the bottom of that agenda, if they have anything to say about it! Even mildly tangential studies get directed toward other non-profits where our freindly M.D/professor/government advisor is also on the board. Will the result be unbiased? LOL. Will any papers or journal articles be openly printed on PubMed? Fat chance. (They may be quoted by expert witnesses in individual court proceedings and various governmental advice-giving, though - because, interlocking.) And that same association, and that same guy? They can also build and promote the cite engine and a standard of 'the more it's said, the truer it is' - because, journals!
Is that long and gnarly enough for you? That one, btw, is a true story which I know intimately well. I couldn't have invented that mess if I'd tried. It took months and multiple people just to document it. And frankly, we wouldn't even have tried, but for someone noticing that you couldn't actually get at the articles behind various paywalls in the first place. But many more examples exist. Usually, but not always, so convoluted. And in most of those, I wouldn't say any evil intent exists or was ever intended. I'm not a conspiracy theorist, really. For that, you need a theory. Instead, I documented a story that just got crazier and deeper as we went along, and this is how it rolled out. In the end, that government agency lost its funding in that area when the facts finally came out. I am aware of at least one of several articles penned for issue-related journal publication based on that case was canceled at the last possible moment, for fear of angering the agency people who would be implicated.
And that's the name of that game.
The point is rather that WE own the data and its products. Because WE already paid for it. To lock it behind a paywall, such that the very people who already paid for it and who may also be those most affected by its outcomes cannot even see it? Nope. Unconscionable, unacceptable. But - the way the game gets played, it happens with very great regularity. Even a student who needs to read that work cannot, without a good chance of failure and a lot of hassle. Even your physician cannot - unless they happen to hold a subscription to the exact journal that published or be on a uni campus where they have access, or similar. It can be such oddball, arcane stuff that hardly anyone inside the scientific community gives a damn - or (as in that particular case), something which could affect thousands hit by a natural disaster. But they should ALL be able to read it freely if they need or want to, don't you think?
Except, they can't. Now, you CAN read whatever the people inside the agency itself chose to write. It may have zilch to do with what the researchers themselves reported, and may address a different topic almost entirely. So that may be useless to you. But, they will honor the exact letter of the law, even if not the entire intent of that same law., which this later rule attempts to repair.
Sorry for length. Truly. But you had to go and ask, didn't ya, lol.