Well - in the case of the CPL student in my school that asked why the airplanes didn't have nailed tires as that would assist in grip on ice. The teacher explained that the airplane, however complicated otherwise, didn't have a "drive" on the wheels, the motion of the plane was dependant on the thrust of the engines.
Maybe some explaining is due: In the more snowy countries of the world (like mine) drivers can opt for nails in the tires for a better grip on ice. It is getting obsolete.