I think you're correct. Mostly, Netflix doesn't geoblock by credit card address because they don't really want to win this battle. Also, having made this decision long ago, it's hard to change policy now without seriously annoying a high percentage of customers. While it is possible for people for obtain credit cards in other countries to work around such a block it's substantially harder than just buying a VPN service. The first sign that content providers are winning will be when selected new content is restricted by credit card address.