Why can't my friend walk if all she has is a broken big toe?

See below. Depending on the severity of the fracture she may not be able to accomodate for the pain in her big toe.

Maybe it hurts. Maybe it hurts. One uses the big toe to propulse or push off the ground when walking so if broken walking may hurt. A surgical shoe would decrease this effect and make it easier. It would also depend if the break was displaced or not and or if it was near the joint line. She may have been warned by her doc not to walk. Usually though, for most broken toes you can walk with a surgical shoe.