If it followed the USPS model there would be a retention fee for the uploader and a transfer fee for the downloader, both based on size. There would also likely be a stipulation that fees not dip below the actual costs incurred which would protect private entities that might wish to compete. (Such fee minimums can be seen with some municipal internet service regulations.)

You're literally describing how content censorship already works on YouTube and Meta. Both companies curate content and have selective - opaque - policies about what gets boosted and what gets deboosted.

Also remember that legitimate creators keep being demonetised for no reason because AI moderation has a brainfart and no human is in charge.

And then there's the clusterfuck around malicious copyright strikes made for bad faith reasons by non-owners.

With public infrastructure there's at least some nominal possibility of democratic accountability - not so much in the US, large parts of which are pathologically delusional about public infrastructure as a concept, but it should be an option in countries with saner and more reality-based policies.