Yea and idk about other parts of the world, but in Romania, the publishing fee is paid in full by the university if the researcher is part of a doctorate or masters programme... So it's just science institutions trading money between each other here...

In a roundabout way, yes a researcher does get paid for their publications but not directly. Universities exist on their reputation and their reputation is determined, in part, from the publications their researchers make. So a researcher who publishes a lot of high quality publications has a better chance of being offered a position at an institution with a good reputation, which can offer to pay them more.