Halloween // Would it be okay to have a candy dispensing machine that uses facial recognition and other biometric recognition?

Would it be okay to have a candy dispensing machine that dispenses candy based on facial, gait, and other biometric recognition to recognize if it was the same person? Kind of like this Chinese toilet paper dispenser, https://sea.mashable.com/article/1621/china-is-installing-facial-recognition-toilet-paper-dispensers-in-public-restrooms

Or would it be a privacy concern?