Context (for those who might not be in academia): many academic publishing companies (like Elsevier) charge exorbitant prices for researchers to get their papers published as open access. Meanwhile, none of these researchers actually get anything in return for it (except for major street cred if their papers get highly cited)
Because the journals existed as massive, financially powerful entities. There were negotiations over open access arrangements a few years back which led to things like "gold open access", which involves papers being free to read, but costing a heckton for the researcher's in "Article Processing Charges". This happened because the journals effectively argued that "even though we're functionally useless in the modern day, and don't even provide services like copyediting or typesetting support for researchers, you can't just make research actually be fully open, because then we would no longer be able to be absurdly profitable. Won't someone think of the profits?!". And then their influence meant the open access agreements were half baked and insufficient.
However, there is a continuing movement that is pushing for actual open access โ "Diamond Open Access" doesn't charge either the researchers or the readers of papers. It's still small, relatively, but it's growing, especially in the global South or amongst independent researchers who can't afford absurd Article Processing Charges. Profit driven journals have prestige on their side, but I reckon that Diamond Open Access will continue to grow as research funding becomes more scarce relative to the amount of research being done.
(Source: the linked Wikipedia page)