They are definitely not doing identification (1:whole_database) for payment, that would be ridiculous.

I'm sure they are matching against very small subset. Most likely they are getting data from mobile phone operators on who's currently around the entrance

I'm also skeptical it would work decently without something else like your cell phone signal to reduce the number of possible faces.

I think the real value of this system is the intimidation factor. It really pushes the idea that the state can identify anyone anywhere is Moscow. It's useful to discourage both terrorism and political activism.

I wonder about the guy at the Houston Astros game recently. The FBI got a tip that a long-vanished white collar criminal (John Ruffo) was at the game. They located the ticket holder and interviewed him to determine he was not the guy after all.

He was reasonably close in appearance, allowing for age progression.

So I have to wonder: Was the tip a high probability hit in a facial recognition database?

or fast. You need a fast system at peak hour.

I found out the other day that it isn't uncommon in some countries (China, India) for metro systems to have security lines, which to me just sounds like a great reason to drive instead.