They're not.
We keep a DVD-based Netflix account around for a lot of this stuff, and I've purchased quite a bit of physical media on eBay or at local thrift stores over the years. It's rare to pay more than $5 or $6 for a good DVD of stuff we're looking for, and then into Plex it goes. Most of it can ship Media Mail if I'm not in a hurry.
As far as I'm concerned, streaming services are good for "I want to watch something; I don't care what." They tend largely trash for "I want to watch this specific thing."
Are you streaming these? what service have they landed on? I haven't been able to find them on the services I have accounts with.