there are shows that there were made on film the film material destroyed in favor of the tape because film storage is expensive, and they never intended to have HD anything back in the days of SD video.
Sometimes a reel of film gets lost for some reason or an entire episode goes missing.
Some of the studios even junked original audio tape master’s and original audio for shows.
Have to rely on fans that taped or recording the audio.
And you also have the case of film-based aka cel shows edited on tape. And redoing them for HD is expensive, it’s basically the process Star Trek TNG had to do as that final cut negative was broadcast masters.
What they do is go back to raw camera negative as if they are doing the show from scratch, this makes no sense for low budget anime OVA or tv shows.
It depends on the show and movie and whether the physical blu-ray or DVD sales or 4K sales warrant such a thing, if not streaming them.
Even Studio Ghibli except for Miyazaki’s latest film has not made the transition to 4K.
Then you have upscales like the upcoming Girl Who leapt through time and the recently released Wolf Children and Summer Wars. Mamoru Hosoda.
I also think Perfect Blue and Paprika were DNR, i’m not sure if those were 4k scans or 2k upscales.
I hope the rest of Artmic works show up or get new HD scans. Its a shame only Bubblegum Crisis has been done. Gall Force i have the laserdisc set and i waited forever for a HD version, i don’t even know if the film still exists or just another tape show.
Like i wish Evangelion episode 16 would show up in its original form on film.