OK, if you go in the album options, the share option is labelled: "Anyone with the link can see these photos and the people who've been invited or joined".

This is very confusing to me, and I like to think I get authentication models. If having the link is the same as being a member, what's the point of being a member?

I think if you're a member, it sill show the photo under https://photos.google.com/sharing for you. So you don't need to store the link yourself to find the photo later.

But that's like a "favorites" list. What's the point of showing the member list of an album if technically everyone is a member?

It still helps you remember who you've shared with, and the likely list of people who can see it.

> *In fact, this UI is basically identical to the Drive UI, including separating the functionality of creating a public, shared link and sharing with a specific person. It's downright surprising that Google Photos acts in a different way than Drive here.

Just a guess, but I'm betting this is an issue with how compartmentalized Google is within itself, that it was just simply two different people had two different solutions to how "links to objects" should work and it simply never occurred to either of them to check what the other products are doing.