A couple of thoughts about this. First, one thing an American would notice upon staying in France for an extended period is how comparatively lackadaisical French shop owners and store employees seem to be about making money.
In the U.S., many small business people work very long hours trying to make a go of it. French workers, while they work very hard and are quite efficient while they're working, are different. They value their time off and this goes for shop owners as well as employees at, say, multinationals such as Michelin or Solvay.
Consequently, besides the closure from noon to 2 or 2:30 in the afternoon each day, and the summer congé (seasonal closure; typically for 2 to 4 weeks in August), one finds signs on shop doors with "fermeture exceptionnelle" (special closure) with a surprising frequency. In other words, it's not that "exceptionnelle."
Other times, shops are closed for seemingly no reason at all -- no sign; no nothing. An example: I moved a few months ago from a large French city to a small town in Bourgogne, and there is a shop in town I walk by nearly every day, and I have yet to see it open. It's a nice shop, at least looking through the windows: beautiful home decorations and some clever lamps (the French seem to like whimsical lamps) but even if I had wanted to pay 159€ for one of those lamps, I couldn't without taking a brick to the window or jimmying the door. Down the street a ways is a health food ("Bio") store. I've been struggling mightily to find silken tofu in France and was hoping they might have some. Who knows? I visited them twice last week because of a recipe I was making that called for silken tofu, and despite the sign on the door saying they should be open, they weren't. It's pretty frustrating.
The big box stores (E. Leclerc; Carrefour, Leroy Merlin, Casino, Auchan, Intermarché, and so on), however, are more similar to American stores in their business practices. They're open when the sign on the door or their website says they'll be open. They don't close at noon. They don't close in the summer. If you need something they sell, you know you can get it with certainty during their posted business hours. That's not the case with many of the small stores in city centers.
So, even if the average French customer is completely in tune with French shopkeepers' practices, it wouldn't take many "fermetures exceptionnelles" before a quick trip out to big box land looks pretty darn appealing.
Coincidentally, we drove down to Vichy today to do some shopping in the city center. This is only my second time there, but I noticed that there are a lot of varied merchants and foot traffic there, so I'm a little surprised to see it on the list of the article noted by Tim.
To close this over-long comment, I, too, regret the trend of seeing "local louer" signs (space for rent) in closed shop windows. There are plenty in my town. But some of the cause of this can be laid at the feet of the French merchant. Now that consumers have a choice, small town merchants may want to re-think their business practices to avoid having their friends and neighbors exercise that choice.