I think it's a very interesting bit of Swiss history. All the work of Dufour (the General of the Swiss Confederation Forces in the Sonderbundskrieg) and his team in measuring, mapping and producing one of the highest quality topographical maps that still holds up today.
But Dufour maps use "hachure" [0] lines for relief, not this type of shading, I think.
It seems natural that people living in the mountains would have a robust topographical tradition.
As you might have guessed, military purposes were a big driver (it was an army general that was initially tasked in producing the first high quality maps covering the whole country)