It's a bit more complex but quality in bakeries varies a lot. First, if something is not called a Boulangerie, then they don't make the bread they sell.

Then there are things like Festival des pains (https://fr.wikipedia.org/wiki/Festival_des_Pains in french) which is a group of mills, provides training recipes and flours. You see there bread a lot (like the Festive baguette). Those are still proper bread and the quality will vary depending on the baker. Most often bakers will have a mix of those breads and their own recipes. The branding tends to make those standard recipes more visible though.

In term of viennoiseries (croissants etc...), most bakers don't make their own and relies on industrial ones. It can be quite hard to spot, the best way to know that is if it mentions "Fait maison" (this can only be mentioned if it is made on the spot using raw ingredients if I'm not mistaken).

I find french supermarket bread not better than UK ones, it's the same technique and same crap result.