In small towns in Tn as a teenager i.e. >13 beer was no prob. All a person had to do was look as if they had put in a days labor (feilds or const) set your $ on the counter and walk withyour beer.
I remember having drinking partys at my parents house. Dad was the PO. My younger bro (13) had a sit down bar in his bedroom so after the Fri. night meeting it would be a sleep over, with more than a few in attendance and plenty of beer for all.