Exactly. I've never understood these laws. People just stock up on Saturday or go somewhere close by where 'blue laws' are not in place.
The laws against alcohol on Sunday are a survival from the days when everything was closed on Sunday. At least that made sense, from a religious perspective: The Bible says you take a day of rest, so businesses should be closed.
Eventually the Sunday-rest concept faded, but anti-alcohol sentiment was strong, so "No alcohol sales on Sunday" is a hybrid of Sabbath-keeping and Prohibition.
I've lived a couple of places where alcohol wasn't sold from midnight to noon Sunday. I'm not sure what the expected outcome of that is! They can't really think many people are going to get up on a Sunday morning and make a decision between going to church or buying booze!