Like all skills, there's a big gap between "easy enough for an amateur to do an amateur job" and "results worth paying an experienced professional to do a professional job." Until we have real general AI, robots will not be capable of the latter outside of tightly constrained situations, like assembly lines.
The pros I know install drywall sheets horizontally, in part so filler pieces don't have to be done while squatting or bending. The filler is in the middle of the wall. I assume low back or knee pain isn't programmed in yet.
I'm just starting on drywalling a repaired section of my basement. I'm only at the "get the drywall from the hardware store to the basement" phase, already that was hard enough and that was the easiest part. Ugh.