Historically speaking, hillsides and mountains are awkward for both homes and combine harvesters. Such land is currently where pasturing is most common.

But such things are always conditional and depend on the tech. If Boston Dynamics robots start building the houses, or picking fruit and herbs on hillside orchards, such concerns probably stops mattering.

I think that it's mostly combination of location, soil and terrain shape. Letting cows graze on a plot of land isn't worth much. If you let the cows graze somewhere that's because you have no way of getting anything more from that piece of land.

Lumping pastures with high class, farming suitable land is a bit dishonest.