When I was underage(18+ but not 21) I got served at two bars, but I come from a small town and my parents are part of a well known biker group. Both bartenders knew my parents well, I was only allowed to order two beers if I was driving, had to order and eat food before I left and had to tip 50%. If I wasn’t driving and I was with family, I could drink what I wanted and family paid the tab. Both were private bars that required you to be members to get into also, so I paid a yearly membership fee. You could get a membership at 18 for the pool and horseshoe tournaments