I don't remember alcohol ever being served in the ground. All drink consumed on terrace was taken in. I also remember games before 1980 when I went to the games as a skinny youth in an oversized Parka, with my brother and his mates' carry outs filling every pocket and the lining.
Having been in the family section at Hampden with kids constantly getting up for drinks in the first half and a pee in the second. I'm not sure It would improve the experience if adults were doing the same.