I'm assuming because most of the content serving happens in Open Connect [0]. And while there may be a ton of server work involved in billing, api, auth, analytics, etc, it probably pales in comparison to the raw transcoding if you take actually serving the encoded files out to clients. From the article, "9,570 different video, audio, and text files" are generated for one show, from 8k resolution source files.

Seems reasonable to me.

[0] https://openconnect.netflix.com/en/