That is because you can only buy it by the case (that is the f**ken law). Would be unseemly trying to get that case into the family station wagon with the kids right after church.
You can buy 6-packs on Sunday --- if you can find a bar that's open. :~(
PENNSYLVANIA: WHERE NICE FOLKS ARE ALWAYS WELCOME AND YOUNZ JAGOFFS CAN JUST STAY WHERE YOU'RE AT