When are the German Stores Ever Open on Sundays?

I recently received an email from a confused American in Germany.  Now don't make a joke...this is serious, as it involves shopping.  This certain lady asked why sometimes, she can drive through her town on a Sunday and all the stores are open, and everyone seems to be "in the know" except for her.  The next Sunday, she decides to try it too...and everything is closed again with imaginary tumbleweeds going thru there it's so quiet.  So what's the scoop with that?  Why are some stores open sometimes, and why are other stores open other than sometimes?

Let me try to explain....as you may know, the Germans have been VERY resistant through the years to open stores, as a general rule, on Sundays.  Believe it or not, it was like that in the US...many, many years ago, before it became the land of always 24 hours.  The Germans always believed that their society would be "ruined" if they started allowing stores to break that last bit of sacredness, by opening on Sunday....no, not for religious reasons, although that does sound pretty good.  I think it has something to do with the labor laws and compensation or something in that direction...or at least that is the official party line, so yes, there is some valid reasoning behind it.

At some point in the government, someone decided there is much more revenue to be had on Sunday and darn it, those politicians wanted to be able to go get that bottle of wine or whatever last minute item on Sunday not to mention fresh rolls Sunday morning.  It started slowly at first with gas stations and stores near major transit hubs being allowed to open on Sundays and holidays.  Then it progressed a bit to include a few more, in particular some bakeries and such.  Then someone came up with this literally translated "sell open Sundays" or "Verkauksoffener Sonntags".

Many city governments and even smaller localities will get with retailers in their city center (or town center) to enable this....it'll happen almost once a month.  And how do you find out about it?  You can either check your city newspaper or the municipality's or town's website (not the tourist one, but the one for residents).  Many stores will also announce it ahead of time in their own literature as well, so keep an eye out there.  There is also a German website that lists some of the dates by region and then by town.  I don't know how complete it is, but I do see plenty of listings there.

Now if I could only figure out the equivalent in French, cause I see many of the towns do it here, at least around the holidays!