Because these are irregularly shaped screens, deeply embedded into dashboards. Not a few gears on a shaft that can be easily worked on. Or a few solder pads to reflow.
Computer screens fail. LCD screens get bad pixels or failed backlights. And that’s in relatively benign conditions. Cars get horrifically hot and cold.
There is no standardized interface for cars. No vga, display port, etc. every screen is a custom job.
I’d love to know how many old screens are available as new replacement parts these days.
No, a screen based display for controls is completely different, and a poor comparison to the clusters of old.
If lots survive, great. At some point they won’t. And they’ll be much harder to repair than gauge clusters. It’s not that hard to comprehend that a million unique, proprietary screens don’t make for easy obsolescence management or combo repair parts as the years go by.