I understand IP (internet protocol) issues since I do network software development. My question might be better asked as who is blocking US Netflix outside the US? Either Netflix themselves or an ISP on the remote end, either contractually or by regulation (law). While I know technology, I don't know international law and commerce. Who forces Netflix or anyone else to inflict this damage upon themselves?
It's a legal thing.
Netflix buys licenses to stream specific shows to specific countries. Each regional Netflix has it's own set of books. So they can't all afford to be as robust as US Netflix, since they have a much smaller client bases to draw their subscriptions from.
Try (effortlessly) to sidestep their geoblocking with a VPN and you are a criminal who who could possibly have to go to jail for video piracy, even though you are paying a subscription to the wrong Netflix.
Research I did a few days ago said that 1.3 million Canadians are using VPNs to illegally buy US Netflix. Now although US Netflix is getting the money, Canadian Netflix is not. Canadian Netflix has to stand or float on it's own merits, and would be able to return a healthier profit and create a better product if those 1.3 million thieves relented, and accepted that they do not deserve superior US Netflix.
Regionally all the Netflix are in (friendly) competition with each other, that if they are not making enough money, a lot of staff will be fired and their library will be gutted, until a more favourable equilibrium is created.