It is a bit like the daleks. Created by a mastermind but he forgot about stairs. Tall with cameras will get stuck under low hanging fruit trees. Ultrasound fine for walls but flower beds less so.

There is a lot of unknowns even for one application.

Another example..I had one with a rain sensor so it avoided cutting wet grass. Sounds good but if there are weeks of rain then the grass does not get cut until gets too long for the mower to cut.