Why not flip that on its side? If you have ever had a parking ticket in Toronto, there's an administrative system that makes you subject to a $50 fine unless you explain yourself. If I post something hateful on the Internet, part of the problem with our system right now is that the response is the Criminal Code, right? There's no good ability to penalize either me, who has published the hateful content, and there's certainly no imposition upon the platform at the moment to take it down or pay a penalty if they don't.
Why not tax the big players and have a public administrative system that has a quick takedown system in the first instance, rather than putting the obligation on these companies to police it themselves?