Why are electrons more mobile than holes?

As we have studied that electrons are having higher mobility than holes, however only very few of us know the simplest reason behind this reason. Higher mobility of electrons is the reason behind the preference of npn transistor  for high speed applications.

One simple reason is that electron is always looking for empty hole (unoccupied state) and is moving rapidly and randomly inside the crystal lattice unless it recombines with hole.  However, hole (empty state) is waiting for electron to come and move only when nearby electron takes it’s place. This is slower than the movement of electron.

Another way we can explain through band diagram. Free electrons are moving in conduction band whereas free holes are moving in valence band. As valence band is more influenced by the nucleus of atoms leading to more scattering, movement of holes in valence band is slower than that of electrons in conduction band.