There's still one person to help at the door, one person to check ID for the alchohol section, a security guard, and clerks that fill up the aisles, refill the shelves, put things back in their place, etc.
Also, they have a kitchen attached to them, and prepare food in it, so they have kitchen staff for that and all the delivery surrounding it.
They also now need to hire engineers to work on the system, maintain and repair it, and service workers to setup and maintain the infrastructure needed in the store.
Honestly, I'm pretty sure the whole things turns out way more expansive for them than hiring a few cashiers. I think the idea is that the extra convenience given to the customers mean that customers will prefer to shop at Amazon Go instead of elsewhere, and that might be worth the extra cost to grow the marketshare.
Also, they have a kitchen attached to them, and prepare food in it, so they have kitchen staff for that and all the delivery surrounding it.
They also now need to hire engineers to work on the system, maintain and repair it, and service workers to setup and maintain the infrastructure needed in the store.
Honestly, I'm pretty sure the whole things turns out way more expansive for them than hiring a few cashiers. I think the idea is that the extra convenience given to the customers mean that customers will prefer to shop at Amazon Go instead of elsewhere, and that might be worth the extra cost to grow the marketshare.