I suspect it is all down to regulation.
Employing someone in France is a huge gamble because it is very difficult /expensive to get rid of them if the experiment does not work.
People generally know when stores are going to be open and plan their day accordingly. The result is people get what they want and the stores do not have to stay open all the time which is expensive.
Smaller commercial ventures are usually family run and there is a limit to what one family can do or want to do. If the french adopted the american model they would all have to work more and have less time free. They may end up with more cash but a poorer quality of life.
If you try to turn France into an anglo-american clone you will destroy much of what you left your native land to find. Just adapt and "go wid de flow".