“when the French have more courage than we do.”
Most are well aware of British and many French evacuations off Dunkirk.
And who do you think was their rearguard?
Would you have volunteered for the rearguard while everyone headed to England for tea?
Yes, some Brits stayed, only a few survived and not much better for the French.
True the French had many issues with strategy, equipment, and some political leaders.
French grunts fought to the end with what they had.
It is best not to take history from The Simpsons.
This was critical in slowing the Germans down in 1940:
https://en.m.wikipedia.org/wiki/Siege_of_Lille_(1940)
When French troops were well commanded and in a defensible position they fought and fought well.
The problem in 1940 was that the cream of the German Army, hit the weakest part of the French Line, and the poorest quality troops.
Most of the troops at the “hinge” where the Maginot Line ended were reservists, and not well led. Add in poor communication and it was a recipe for disaster.
The French learned a lot of lessons in May of 1940, but by the time they could apply them, it was too late.