The Pilot is not the best episode for comparing video quality across distributors and streamers. It was edited on film in contrast to the rest of Season 1 being edited on analog videotape and Seasons 2 - 5 being edited on digital videotape.
Disclaimer 1: My understanding of all this is a little shaky, so please be aware that I may have made many errors as I try to explain a confusing situation to myself.
I haven't watched SLIDERS on streaming, but every streaming service uses video compression. I've read that Netflix compresses its video into a lossy format that loses some sharpness and eliminates most of the film grain to reduce bandwidth. They transmit the video. A sharpening and noise-addition layer is applied to the received stream. They are probably doing this for all content and not selectively. This approach is fine for HD digital video or film converted to HD digital video.
However, if the video is standard definition, Netflix's approach is going to diminish whatever limited merits the SD file had in the first place: what was already blurry is blurrier and sharpening makes it blockier.
There's also Netflix's standardized streaming format: 24 fps (actually 23.976)with videos in a 1:1 pixel aspect. On average, DVDs of older TV shows would be 30 fps (well, 29.97), in 720x480 resolution in a 9:8 pixel ratio (I'm basing that on what I've read about DEEP SPACE NINE DVDs, but pneumatic can correct me).
Netflix's pixel aspect conversion turns 720x480 files into 576x432. Then Netflix applies inverse telecine to get 30 fps frame rates to back to 24 fps. The reduction creates blur, and the inverse telecine makes things worse for SD TV shows specifically.
From what I've read of pneumatic's work and read on my own: a lot of film-based projects were converted for home release, changed from 24 fps to 30 fps to match the 30 fps of a CRT television.
When playing meant-for-CRT 30 fps files on modern HDTV displays, the interlaced 30 fps video will stutter without conversion. Inverse telecine converts 30 fps video back into 24 fps. Inverse telecine combines multiple frames into single frames to restore the original frame rate. This is effective for playing 30 fps content that was originally shot and edited in 24 fps film.
However, most 90s TV shows were only shot on 24 fps film, not edited on 24 fps film. Instead, the 24 fps film was converted to 30 fps videotape via 3:2 pulldown. The conversion created new frames: three single frames, one duplicated frame (3:2), to reach 30 fps, and also separated the frames into interlaced fields for interlaced CRT display.
As long as there's a consistent cadence of three single frames and one duplicated frame, the video looks consistent. Unfortunately, production would edit the finished episode together by copying different shots from different videotapes onto the video master. In addition, the master videotape would have sequences that only ever existed in a 30 fps format: special effects, specific video effects sequences.
I'm guessing here, but it looks to me like each transfer from analog tape to analog tape seemed to distort the cadence further as fields and frames were mis-duplicated or dropped, further confusing the cadence.
The final episode would be a jumble of inconsistent cadences that might look fine on a CRT TV but shows artifacts and mismatches when a player or streaming services uses inverse telecine. The confused cadence means that a streamer or a disc player using inverse telecine doesn't have a consistent cadence for combining mismatched frames for 24 fps display.
As a result: there's resolution loss when half of the fields are absent. There are artifacts when mismatched frames are combined. This is probably why pneumatic kept seeing interlacing issues that he said looked "baked in" and why the frame rates and cadence were so inconsistent within individual files. And because streaming is compressing the file as well, it looks even worse than DVD.
The jagged edges are periodic in "Summer of Love", "Last Days", "The Weaker Sex" and "The King is Back" but severe in "Prince of Wails", "Fever", "Eggheads" and "Last Days". My guess is different episodes used different telecine hardware for 3:2 pulldown conversion, some of which created the 30 fps frame rate with poor frame duplication and inconsistent cadence, and some of which did a better job.
"Last Days", for example, suffers from telecine judder where the others don't, so it was transferred on different equipment than the rest. There are different telecine tools: flying spot scanners, line array CCDs, pulsed LED systems. Give the inconsistency, it's likely that Season 1 of SLIDERS used whatever telecine tools were available at the exact moment that film came in, and not every episode used the same process.
I think it is also likely that whatever process was used to transfer the Season 1 episodes' analog videotapes into a digital format for DVD release created another level of generational cadence distortion.
Season 2 Upgrades
Most of these issues seem to vanish with "Into the Mystic". Season 2 benefitted from switching to digital videotape and with that would have come a new film-to-videotape telecine process.
I'd be curious to know how SLIDERS in Seasons 2 - 5 look on a streaming service. With the DVDs, I don't recall any of the Season 1 interlacing issues on Seasons 2 - 5. They probably exist, but they don't seem as noticeable.
Two possibilities present themselves: digital videotape has some final process to make the cadences more consistent. Another possibility is that the telecine process for digital videotape ensured that sequences could be transferred from editing videotapes to the video master to DVD digital files with a lower level of generational loss or cadence distortion. This would isolate cadence issues to sequences where material from different videotapes are put in sequence with each other.
It could be some combination of both.
I have to think that Netflix's approach is likely the industry standard and other streamers would just compress more or compress less.
Probably, the solution could be at the studio level: studios can use a more pneumatic-style approach to their old SD 30 fps video library. They could get their material back to 24 fps themselves via QTGMC & TIVTC which provide field weaving, frame matching and selective frame discarding rather than inverse telecine assuming the cadence is consistent. They could use neural network upscaling to bring it to 1080p in a 1:1 pixel aspect ratio. They could provide those files to streamers and streamers won't do downscaling or frame rate conversion.
Disclaimer 2: Please please please please please do not ask me to contact NBCUniversal about this. It's not my job to provide unpaid labour to a multinational corporation's video on demand department. I care about an intellectual property that happens to exist on one of their ledgers, but that doesn't make me their slave.