It wouldn't be surprising if DVD licensing costs are a factor behind the pricing, as the patents behind the technology still aren't cheap. However, you don't really need to pay anything to watch these titles -- free apps like VLC will not only play DVDs, but many of the formats that Windows 10 can't handle out of the box. And did we mention that the official software doesn't do Blu-ray movies? Unless you're holding on to a large DVD collection and insist on using first-party programs for watching those DVDs on your PC, you'll probably better off either trying an alternative app or signing up for a streaming video subscription.