Why only scan at 2K?

[Count Orlok]

I hope this doesn't come off as a stupid question, but I was curious.

Since we're starting to see 4K in the home, why are some movies finished or scanned only at 2K? Nosferatu was given a 2K scan, while The Cabinet of Dr. Caligari was given a scan at 4K. I can assume Nosferatu was only given a 2K job as the print is generations away from the court ordered destroyed original negative, while there are no release prints of Caligari at all.

Scream Factory does this as well. Warner Brothers even scanned Gone With The Wind and The Wizard of Oz in 8K.

Is money a factor in it? Mad Max and The Martian were finished at 2K, which were slightly upscaled to 4K for their UHD BD releases.

What usually determines the choice between scanning at 2K/4K/8K?