It's accessing the internet from a different IP, not a different location, the whole idea of an IP (without additional information) being equivalent with a proof of physical location will most likely not hold up as a legal concept in a higher court. So called geo-fencing by IP only is fuzzy by definition.
The copy is licensed since it's made available by the distributor to the customer. It's the distributors duty to the determine if a customer is eligible for purchase or not, best way would be having to provide a verifiable invoice address within the region of the granted license. An IP is a best guess at best, but not a verifiable proof of the physical location of the end customer. Netflix doesn't ask for an invoice address, Amazon Prime does. Amazon also has siloed accounts for each market where you would have to have multiple subscriptions in different countries to access the local offerings, where as NETFLIX has only one global platform. If an US-resident purchases a US-NETFLIX subscription travels abroad for a short or long period it shouldn't make a legal difference if a private VPN to the home's IP or a commercial VPN service is used.
By all enforceable concepts the place of purchase of the subscription is the relevant thing for having a valid license for private use, not the place of consumption.
Also I can't see why the first-sale doctrine wouldn't apply here either. Rights holder sold a distribution license to Netflix under certain restrictions (first sale). With Netflix distributing the copy to the end customer.
http://en.wikipedia.org/wiki/First-sale_doctrine