[RegW]

10+ years ago I had a job which involved developing/testing geo-restricted software in another country. Eventually each VPN exit point would get marked up as such, and I would have to switch to another.

So if posts were marked with the country of origin or VPN, that might be enough for most people to evaluate the intent of the post.

Of course things have changed. There might not be so many IPv4 addresses around to trade, but IPv6 has probably changed that. And it's probably hard to know how long an address was used by a VPN before being traded back to a telco.