Too Long; Didn't Read
Netflix Japan is an interesting market where people actually still buy and collect DVDs. A DVD of a popular Ghibli film like Spirited away still goes for $25-$40 USD used used used. Netflix is owned by NBC so they have strong powers backing them. Not only that, Japan is a market for people still buying and collecting DVDs. Netflix Japan would be most well-received there. It's not clear why they're not available in the UK, but none of them are on Netflix Japan.