Theaters are probably not in a big hurry to do recordings that compete with live performances. I've been told a lot of it is rights issues associated with the performers, playwright, etc. though.
Personally I find it a pity we don't have quality recordings of most theater. How many great performances are lost to time? If you're into opera, the Met's Live in HD are great.
ADDED: A fairly small local theater I have a subscription to did make some digital recordings during COVID. But they were only available for a limited lime and weren't free.
Does it matter though? Did we really need to archive everything ever created forever? People made such a big deal out of things like geocities being shut down, but does anyone actually ever look through what was archived?
Sure, saving some of it is useful so we can look back and reflect. But we don’t need all of it. It’s mostly junk.
I mostly favor what archivists and preservationists do. But I don't really disagree. Some things are important (and you may not know what ahead of time). But there's nearly an infinite amount of paper with black characters on it. A nearly infinite number of photos. How much video of conference presentations do people watch a month after the fact? A day?
Some stuff is interesting to preserve. I scanned a Year in Life of Development book from a long-ago company and it's a neat look into mid-1980s computer development.
But you can't save everything and you probably just need to let go sometimes.
https://en.wikipedia.org/wiki/List_of_lost_films
https://en.wikipedia.org/wiki/Category:Lost_television_episo...
https://en.wikipedia.org/wiki/Lost_literary_work