Is China that successful at it lately? I see a lot of posters and info from China getting around the great firewall, and my understanding was that they don't really care if 1% of users do that so long as it mostly holds and only the technical minded or really fixated will see it.
So there is a route around censorship, but maybe the public doesn't really care about it.
I'm not sure whether it's 1% or 0.1% or only Xi Jinpin can access YouTube. China can adjust the surveillance level dynamically. It's a matter of cost and effect.
There is also the difficult reality that the government doesn't need to block vpn entirely, but just make it a credible risk of being detected. If you have to worry about the state police barging into your home, you are likely to decide it isn't worth the risk and self-regulate.