When walls meet topography, they clean up in section but not in plan... why not?

There are plenty of work arounds using filled regions and building pads, but for a simply slab on grade situation, it seams like a lot of work just to not have the earth hatch overlap the wall hatch. I've found numerous work arounds for this myself, but am wondering if there is an official or best way of doing this and why the difference between plan and section.

Thanks,