I don't have Criterion available in my region nor can I find DVD/blurays anywhere so sailing the high seas is the only option for me.
They have a rotating selection of Criterion films. Heavy on documentaries (of the plays-the-festival-circuit variety, not the narrated-by-David-Attenborough variety) too, if you like that sort of thing. Usually several fairly-recent good movies as well. It's where I watched Ex Machina, for example. Kids' features really lacking, mostly low-quality stuff that would have been (maybe was?) bargain-bin straight-to-VHS material back in the day. No substitute for PBS or Disney+ for that purpose. Material for adults is much stronger.
Views are limited per-month but unless you consistently watch more than a movie a week on that service specifically you'll never have a problem with it.
I've got an address that qualifies for two library systems, and the one I'd normally use didn't have it, so I had to get a card for the one I'd practically never use otherwise to gain access to Kanopy.
Last I checked, Monterey Public Library has Kanopy and anyone who lives in California can get a card there.
HBO Max has a portion of Criterion's canon plus a lot of Turner Classic Movies (American movies 1930s-50s).
I'm the reverse of you - 90% of the time I watch films made before the 1960s, and these two services have a bunch of what I watch. Still gotta torrent or rent from iTunes every now and then though.
I wonder why not. Imagine a Netflix marketing campaign claiming "we have all the great movies of the early 20th century on our streaming platform!" Maybe target senior citizens. They could just rip the movies from YouTube since they're in the public domain.
To give a HN safe-ish link, here's entry #11, The Thin Man (1934) on the archive
https://archive.org/details/the-thin-man-william-powell-myrn...
If that's not a good encoding you can easily find other sources.
If that's against your policies, many of these are available on Amazon
The catalog is based on the recommendations of famous directors, and you end up with a lot of very high quality movies.
You can also find full length public domain movies on archive.org.