Yes but China, Russia, Iran, etc all have national-level firewalls in place. You can go in China and chances are your VPN won't work, and if it does the whole country is fucking network-hostile (like I've seen reports of the USB charger ports in hotels trying to hack into phones).
UK, as far as I know, doesn't have any kind of similar national level firewall. Nor does USA or most other 'civilized' nations.

And without that national firewall, all these laws are crap. Because unless you're physically prevented by the firewall from downloading or using VPNs or similar tools, all the laws in the world are just a padlock on a cardboard box.

That's true, but the kind of lockdown on the Internet that China does can't be done with just regulation and mandates.

There is an absolutely mind-boggling server infrastructure managing the routing and filtering at every Internet point of entry/exit in China, and it is directly physically filtering traffic headed for consumption by people in China.

Its nickname, "The Great Firewall of China", while hilarious, is an apt analogy for it. They literally built a barrier around their country's Internet borders to keep out unapproved information, and probably Mongols.