Wait, so it's actually a standalone, DRM-free download? If that's the case, then while the term is still somewhat misleading, it's considerably less so than I assumed.
Not DRM free, but unlike most streaming services Apple TV will download purchased media via different countries or VPNs and has no time limit to watch the download. In practice, it "just works". Buying all 4 seasons individually would be 4x$13=$52.
I don't see how it qualifies as a legitimate download or ownership. You cannot save the file to a disk you control and you have no way to ensure you have continued access to it. Apple or the IP holder can cause this "download" to dissapear from your device/account without prior warning. Its actually written in the terms.