When I worked in the filter industry ACMA added a handful of sites to the blocklist each week. During the same interval teenage boys at the schools that purchased the filter product I worked on managed to find HUNDREDS of new anonymous proxy servers each week.
2. The Darknet.
By the time Gummints notice a technology, it's old hat. The web is probably not what the kind of vile swill who seek kiddy pr0n even use any more.
We has it.
Filtering the web was barely feasible ten years back when this cockamamie idea was dreamed up. Nowadays you can get home broadband plans with TERABYTES. Filter that.
We live in a post-secrecy society. Remember what happened when the DVD CCA tried to supress a leaked encryption key?