( I grew up with BLUE law's...and yeah it made me BLUE many a Sunday... I am surprised they still do this_)
It;s a throwback to Christian Times, fanatic church goers demanded that on the Lords Day of Rest the state should intervene and prohibit or atleast limit sales of " The Devils Drink" past 12:00AM, Saturday nite until 12

oam Sun. nite. No alcohol sold.
So the black market in alcohol sales has blossomed on Sundays, but you gotta know where to look...