In the defence of our backward socialist planet sharing counterparts, this ensures a low probability of hair parasites (provided proper sanitation) in the general populous as well provide continued employment of the nations hair dressers. Two birds, one stone policy.
The elderly men of N.K. are luckier and allowed too grow 3 inches long head hair, over the 2 inch maximum of head hair for younger men.
Edit: I always have hair length under #5 razor, #3-1 for the brush cut but you know hat head and 'back pattern baldness' > needs it IMO. K tks