Can a person drive after a leg amputation?

Yes. Yes. With the proper set-up and training many amputees enjoy the freedom of driving!
Yes. If the leg that was used to drive is the one missing the car can be modified. The person can learn to drive with the opposite leg as part of their rehabilitation process. If both legs are missing the vehicle can be adapted to be driven with hand controls.
Yes. It is generally recommended to use one leg to control pedals. However, for bilateral amputees, automobiles can be modified with hand controls.