Door people, bouncers, floorwalkers, or bartenders can assist with checking ids and monitoring for intoxication, but the server is legally responsible and will be the one who receives a violation.

This refers to the "Responsibilities of a seller or server".

The most critical obligation of a Seller-Server is to take after the laws expected to keep the offer of liquor to minors, inebriated people, and non-individuals from a private club. The individual who really serves, offers, or conveys the mixed refreshment is lawfully in charge of the deal.