He came to Earth as a baby and grew into adulthood. Even if he had some biological Kryptonion oddity that prevented facial hair, the hair on his head still changed over the years, so I assume it grew. How could he get a haircut? Scissors couldn't cut through his hair.

Did his adoptive mother (and whoever cut his hair after she died) have to expose him to Kryptonite in order to give him a haircut? What if Earth had a crisis when he was in the barber chair?

Too confusing.....I think I'll go back to chipping!