Amazon Go

I'm guessing it's not as simple as they make it look in the video...unless the food tags have some kind of RFID/Bluetooth to communicate with the phone in your pocket...maybe the grocery bags? Even with cashiers sometimes they don't know what the price is...also some things are sold by the pounds...where is the scale? What if you pay then walk back in again? You get double charged?

No need for them to talk to your phone or a smart bag. They just funnel you out through a lane and scan them there if they're using RFID. They can also do this theoretically without using RFID at all if they can solidly determine what product you're taking off the shelf, maybe by using good cameras to see where you're reaching and if you're placing or replacing the item that's assigned to that slot. They've been tracking you since you entered the store so they know what Amazon account each person is associated with so they just combine the 2.

As for loose weighed items it doesn't look like they're selling those. /Everything/ in the promo shot of the store is already packaged and they look like they're going for more of a convenience store food source than a traditional grocery store.

It would take many cameras working together to pull this off...what happens when you drop out of sight? Feels like a big vending machine...If they're not competing with big grocery stores, then this won't scale well...right?

If the system relies on tracking you constantly from the moment you enter they'll have as many cameras as they need to cover the whole store. For just tracking the person you really don't need too high of detail just decent coverage and if the system is using CV to determine what you're taking off the shelves instead of RFID(ish) tags (which makes sense given the cost of applying tags to every item) then they've already got way better camera coverage than they need to just track you around the store.

Really this whole thread is all just rank speculation that'll be mostly confirmed or denied once a store actually opens and people can look around and see what's going on.

Also as for scaling it's a fixed cost to cover a larger area compared with a variable cost if they're using RFID to scan when you pass through the turnstiles so really a camera based system probably scales better than a tag based system.