It gets more and more difficult to make a robot get up when it gets heavier and taller than about a foot.
There can be tremendous weight and pressure on the entire robot to try to make it get up so this is quite a challenge.
When a human size robot falls there must be consideration made for it breaking some of its parts or hurting someone or something that it falls on.
Usually a toy robot will bend its arms all the way around and try to push itself back to a standing position.