Does she take them off every time she drives, meaning morning, noon, or night or only after a very long day after wearing them a long time. Does she remove them in any weather, cold hot rain snow or only if its real hot and sticky? Does she only remove closed toe pumps or all heels even strappy skimpy sandals? Maybe she feels she can control the car better by having a better feel of the foot pedals in her bare feet. I have known many ladies who remove them for that reason including my wife. Or maybe she feels more relaxed and comfortable behind the wheel without her shoes confining her. Or maybe she is concerned her heels (especially spike heels) could slow her reaction time to hit the brake pedal in an emergency. Many other women feel their high heels place their right foot at an uncomfortable angle in pressing the gas pedal. See, many reasons.