# How are energy states of photons reason for frequency independence in Compton scattering

I am reading on Compton scattering, more specifically on how Compton interpreted his results. He observed that the frequency of the scattered radiation was independent of the material used, so he assumed that the scattering was due to photons hitting electrons. The textbook from where I am reading this from states that Compton had some a priori justification from considering the fact that a x-ray photon has more energy than a ultraviolet photon. Furthermore, from the photoelectric effect the energy of an ultraviolet photon is comparable to the minimum energy with which an electron is bound in metal. How is this a good justification? Wouldn't it be enough to base it from Einstein's prediction of the photoelectric effect? That way only one photon produces an electron and is therefore surface independent.