France, and Britain were the reigning power in Western
Europe.
France especially, as it was their turf. All their men and
equipment were there.
And the French were a very big and substantial army. That they were
not as powerful as the Germans were already a sign of their
weakness of will. Germany was quite broke after WW1, was under arms
buildup control and yet they were able to surpass the French in
armaments.
And they are next door to each other. How can the French not know
of a arms buildup? If they did not bother to check on Germany, it
is again a weakness of their part.
Take for example us in SE Asia. Singapore would never let Malaysia
or Indonesia have a more powerful military force than us. To let
them overtake us will be a sign of complacency or weakness of
will.
It was a published fact that France had more and better tanks than
Germany at the start of the war. They just didn't know how to emply
them.
The British had an Expeditionary Force on Mainland Europe. But
you're right, the Brits also made the same mistakes and were as
weak as the French and luckily they had the Channel to escape back
to.
But the quality of the Brit soldier had never been in doubt. These
people had fought on nearly everyone in every part of the world
since history and are known to be mostly good fighters.