Well, he's certainly not a temporary driver from Friesland :-) and he probably "practiced" on less extreme surfaces first.
The gradients are a question of engine power. What really surprises me is that the tires (almost always) have enough grip. Even when the thresher drives over a pile of straw, only the rear wheels spin a little.

With the best will in the world... Switzerland has enough flat areas that are better suited to farming than steep slopes like these. Depending on the location, you could grow wine on these slopes. But traditional pasture farming would certainly make more sense. I can't imagine how farming can be profitable in such regions.

The machine is pointless. When threshing takes place, the rain comes and washes away the soil. If you can't grow grain there, you don't need to thresh. I recommend meadows and sheep.

I don't care about such harvesters (although I know they are needed), but I know that my colleagues are fascinated and I shared the material with him