They do have those, but the leg mechanisms don't have the same dynamic range as a humans' so they end up getting stuck in doorways, narrow stairwells, or other places which assume bi-pedals. Making them narrow enough to fit, makes them too short to reach the same heights assumed for adult humans, so they can't do the same thing.
The height vs width form factor kills the whole idea as a general solution.
The height vs width form factor kills the whole idea as a general solution.