Why can only electrons transfer from one body to another body in frictional electricity?

(N/A) In an atom,protons are located inside the nucleus and are tightly bound by the strong nuclear force,which is the strongest force in nature. Electrons,on the other hand,revolve around the nucleus in outer orbits and are bound to the nucleus by a relatively weaker electrostatic force. During friction,the energy provided is sufficient to overcome the binding energy of the outer electrons,allowing them to be transferred from one body to another. Protons,being deeply embedded in the nucleus,cannot be removed by such small amounts of energy.