Typical knee walker cart you have to steer with both hands at all times. Knee walker scooter carts are a kind of a vehicle that you ride as transportation. On the street they can go really fast, and require brakes like bicycles, and they are almost the size and weight of bicycles too.
When you are injured and you have work to do, you hardly think about racing in the street. For your home and office daily grind you need something really small and light that is part of your leg and you have your hands free to do what needs to be done.