I will hasten to add I signed up for a 7 day trial of HBO Now when I was in the US and let it lapse. I am not a current subscriber.

Anyway I guess I am still on their mailing list and received this today as an update to their T&C's.

"Clarified in Section 24 of the Terms that we may use technologies to verify that users of HBO NOW are located within the United States, and that users are prohibited from using technologies to mask their locations"

Interesting...

I am not aware that Netflix or Hulu have such conditions in their agreements.

Of course it's all down to enforcement really. With a VPN I suspect it would be pretty much impossible to verify if a user in in the US (so long as they are using a US credit card). With a proxy server it might be easier if the DNS proxy provider terminates with a fixed set of IP's.