I’m not the most researched but let me take a stab. Because in 2008 Alex Acosta gave him a non-prosecutorial agreement that wiped out federal crimes - despite that (and after the Miami Herald published a big report in 2018) SDNY worked to find charges that could work around it, and they landed on sex trafficking in order to make the later arrest stick.
Additionally, after Epstein’s death in 2019, Maxwell was fighting her charges and I don’t believe she was convicted until 2021 and her appeals (I think) are still pending. Criminal files involving sex with minors don’t become public.
This normal handling of sensitive information was just seized on by QAnon and right wing podcasters looking to feed into the pizza gate stuff that Dems run a pedo cult, and it was a convenient way to attack Biden: “who are you protecting!?” “Release the LIST”
Meanwhile Trump and Epstein were friends for twenty years and victims talked about meeting Epstein at Maralago - and now Trump won’t shut up about how this is a hoax made up by Dems. Ok sure