Look, OUR tradition recognizes Sunday to be a special day. Yes, it is based on Christian tradition, but so what? I doubt most people here would last two minutes in 18th, 19th, or even early-20th Century America if they can't even handle the Blue Laws.
How do you know what OUR tradition is? MY religious background would deny you any alcohol, any day of the week. Since when is a tradition a good basis for a law? Yarmulkes have a long tradition behind them in Judeo-Christian tradition; shall we pass a law that requires them being worn? How about mandatory facial hair for men?
No one is forcing you to forgo your traditions; you can easily NOT make Sunday purchases of booze. If the tradition is so strongly held, I am sure booze sellers will quickly find it unprofitable to pay employees, and stop selling it. Or, maybe the real tradition here is hypocrisy, because both you and I know that blue laws aren't stopping the booze drinking on the Sabbath.
When you're being chased by Indians and grizzly bears, you don't have time to worry about Sunday liquor sales. Besides, anyone resourceful enough to survive then can figure out a work-around such as home distillation.