They are under public domain. But they still could theoretically distribute them. Theoretically, pretty much anyone could, but most of this list is just essentially lost to time. They couldn't even if they wanted to for a lot of these. They put in a good bit of work to republish and remaster a select few pieces of work forever but the vast majority of stuff just sits and rots. The same is true for videogames. A small slice gets recycled and republished as some retro game pack or whatever. But most of it gets ignored.

But sure, let's go to more modern examples. Are all of these easily acquired "new" these days?

https://en.wikipedia.org/wiki/List_of_Universal_Pictures_fil...

Agreed they could, and the singular probable reason they don't is "cost". I'm with you, though - I think archivists / pirates play a vital role in media preservation and there should be carve-outs for certain use-cases. There was a gal who recorded thousands of hours of TV on video cassette tapes, which ended up becoming incredibly important / valuable some decades later.

https://www.atlasobscura.com/articles/marion-stokes-televisi...