Here's why:
* "Fatherland" is a Germanic term (Vaterland). It's common in German-speaking countries like Germany, Austria, and Switzerland.
* The French equivalent is "Patrie". This word translates directly to "fatherland" but is much more commonly used in a broader sense to mean "homeland" or "country."
* "La France" is the most common way to refer to the country in French. It translates directly to "France".
While "Patrie" is used sometimes, especially in patriotic contexts, it's not the primary way French people refer to their country.