Beer vending is not illegal. There are quite a few companies that operate beer vending machines where all you need is their preloaded RFID card, and away you go. No supervision
iPourIt: "It’s estimated that self-serve beverage technology is operating in well over 340 locations nationwide at the time this document was written. Self-serve alcohol and iPourIt beverage dispense technology is currently legal and available in 45 U.S. States." https://www.ipouritinc.com/abc-regulations/