Re: The method of enforcement is simple.
"Block the traffic of those who seek to hide behind international borders. This obviously has many practical difficulties but can be done, especially to large companies with a well known addresses."
Umm, no. The *specification* of enforcement is simple, as you describe. However, the *method* is considerably harder, for several reasons. For one, the "well-known addresses" you speak of would have to be blocked at every border router in the legal jurisdiction trying to block. For another, they don't include the addresses of people mirroring or providing tunnels to the restricted content, and whilst *that* may be illegal in your country is certainly won't be in your neighbours, so you'd have to add "every foreign mirror and proxy" to that list of addresses you are blocking on every route in. For a third thing, the address you are trying to block might be a dynamically allocated one, so you'd have to snoop DNS servers to keep your huge list up to date.
So it *can* be done, but it is rather expensive. The Chinese seem to spend quite a lot of effort on it and after all that effort they still rely on "disincentives" for people who uncover errors and omissions in the block list.
Of course, if the IP address space were more cleanly aligned with legal jurisdiction, it would at least be possible for people to *know* whether the site they are doing business with is in the same jurisdiction, and therefore sue-able in the event of disappointment. However, that's solving a slightly different problem. Specifically, that's "giving users the tools to protect themselves from stuff they don't want" rather than "giving government the tools to protect people from stuff they do want". In a free society, the latter is impossible whereas the former is relatively simple once you've figured out that this is what you should be trying to do.
But you are right. The present situation is legally intolerable, so ultimately they will figure all this out and we will get an internet that is as safe as the street where you live. (Hmm...)