But of course that's also a larger problem in academia where tenure expectations are often based on the reputation of publications, which usually emphasizes publication in "high-quality" journals... and those are often older ones that are part of these publishing empires. Shifting to open-access publication for research requires commitment from many major researchers in a discipline to actively promote open-access journals and shift the focus away from other journals... but junior scholars often can't take such a risk and publish where they know others will evaluate their work as "influential," regardless of access. Putting stipulations on grant money like I mentioned above might solve some of these issues, since it will drive researchers to find ways to publish and/or drive journals to find ways to make such funding more accessible.
The golden rule is that "He who has the gold, makes the rules." Open-access publishing is expensive (though there is a large variability in the cost). Payment for this has to come from somewhere. It will be budgeted into grants, but funding agencies are not known for being generous and it is difficult to know how to allocate funding for open-access publication. Universities may also have internal funding available to support open-access publishing. As a researcher, if your funding comes from a source where you do not have the final say (e.g. it is held by the university to fund papers they deem "exceptional", or held by a superior who wants to save it for papers they care about) then you can either go to a non open-access journal that will let you publish for free or not publish your finding (which contributes to the lack of publication of "uninteresting" null results).