In fact, they often make special funds available to pay these charges. As long as there is strong demand by researchers to publish in these journals, they will have to pay up or accept subscriptions. And there is very strong demand, because it affects researchers' long-term career prospects: https://medium.com/flockademic/the-ridiculous-number-that-ca...

That said, funders are also somewhat complicit in it by deciding who to fund based on if they published in those journals. Which is the result of those decisions being made by academics who typically cannot read all the research of all applicants: https://theconversation.com/why-i-disagree-with-nobel-laurea...