I didn't know in advance why Siri can't access my photos (turns out it's because indexing isn't done) - at the beginning I thought there was some sort of other problem. Later I figured out (after going through privacy/permissions stuff) that it's too stupid to know why it can't see my photos.

Amateurish.

I'll answer your question though: because it doesn't show anywhere the progress of the indexing.

It's on the list there alright.