Huh? Some people still buy discs. Sorry you don't find it practical, but I myself enthusiastically bought it when it was released on Criterion because I have seen it many times over the years. Many films, I am content only to own the film on a digital platform. Criterions are different in that they usually contain enlightening extras. Unmarried Woman is no exception.
Most of today’s world doesn’t find discs practical. They’re going away, and I’m happy about that because the last thing I want in my world is more stuff. BUT … that presumes that everything, including niche titles, be widely available in high-quality streaming for a reasonable fee. None of that is currently true for this title, which was as mainstream as there was. You can like discs all you want, but this situation is completely unreasonable and not sustainable.
As for extras, there’s nothing giving discs the monopoly on these bonuses.
Streaming purchases offer them also.
And finally let’s not forget that the fifteen-year-old Blu-Ray is hardly state of the art now. Yes there are a few 4K HDR discs, but most titles are available in 4K Dolby Vision only from a streaming service. That will not change.
You can take it up with Criterion. There are certain notable films Criterion has licensed for release on discs though the films never appear on streaming not even the Criterion Channel. You are correct about Unmarried Woman. Another would be Altman's Nashville which I have never seen on streaming.
Nashville is available to stream by purchase from iTunes and Microsoft, but can only be rented by Vudu. Pretty stupid for a widely distributed film nominated for five Oscars including Best Picture. Perhaps someone can explain how this benefits anyone?
I am willing to wager those versions are the film only and don't contain Criterion's extras. It has never appeared on Criterion Channel or its now-defunct predecessor Filmstruck, though Criterion Channel has gotten much better about putting up many of the titles in its collection with their full extras.