Abstract: One variation of a method for processing transactions at a vending kiosk includes: at a first time, capturing a pre-transaction image of a shelf arranged within the kiosk with an optical sensor; in response to receiving payment information from a customer, unlocking a door of the kiosk; at a second time succeeding the first time, capturing a post-transaction image of the shelf with the optical sensor in response to closure of the door; detecting a difference between the pre-transaction image and the post-transaction image; based on the difference, flagging a portion of the pre-transaction image for review by a remote human operator; and, in response to identification of a product type corresponding to the difference by the remote human operator, billing the customer for a cost of the product type according to the payment information.