The Sunday sales thing is a religious law.
Was, not is. Jesus got the law on the books, but business owners took charge of it long ago. Most of them paid their legislators to overthrow it -- but there's a special class of retailers whose demand is inelastic enough that they don't need 7-day availability.
We rarely buy a bottle of liquor on impulse. It's an anticipated purchase, and we plan ahead; once in a while, if we're in a 6-day jurisdiction, we get caught without booze and we remember it next time. Sunday closing may reduce sales a little, but it reduces overhead much more, especially for a small merchant. So, at least here in Colorado, you could drink in a bar on Sunday but not buy package liquor, until we forced a change a few years back.
The same effect is even stronger with cars: we never forgo a car purchase because we can't buy it on Sunday, and Colorado still doesn't have Sunday car sales.