I taught university classes from 1981-2001. In 1985, they raised the drinking age and many institutions banned alcohol from campus. Of course there was student drinking on the sly.
But I would have end-of-term parties for my classes. I’d bring chips, cookies, soda and juice–and a little something to spike the soda and juice. Originally I’d bring wine, as that was traditional, but as things became more repressive, I switched to vodka or rum.
These were joyous events and the students loved them. I never heard any complaint, as they were mostly genteel affairs, with no one getting really drunk. Needless to say, I did not ask for ID or make any attempt to restrict access. Some of my students were certainly under 21. I had a distinct political opposition to the drinking age laws and thought of this as civil disobedience.
I did this for 25 years, until an unsympathetic colleague found out and proceeded to get me fired.
My years of experience and degree allowed me to find work again fairly quickly. I’m pretty sure that if I’d been caught earlier, I might have not have had a teaching career. “Non, je ne regrette rien.”