The requirement for pilots to be certified fit to fly by a medical doctor is a universal feature of aviation regulatory bodies. The International Civil Aviation Organization sets the standard, which individual states can modify. According to ICAO, “To become a professional pilot or an air traffic controller, an applicant must be in normal good health (including normal hearing, normal vision and normal color perception).”
In the U.S., the issue of whether all pilots should require medical certification was raised when the FAA published the regulations governing manufacture and operation of light sport aircraft (LSA). Although glider and balloon pilots aren’t required to have a medical, the FAA has resisted efforts to permit other types of pilot to fly without a medical. Yet the LSA rules allow pilots with valid driver’s licenses to fly LSA, which are basic two-seat airplanes with hard limitations on speed and maximum weight.