I've noticed that people with afro textured hair especially tend to grow out their hair after getting a HT. This is done to give the illusion of density, because at lower level cuts, the difference in density in certain parts is clearly visible.
I believe the same might be true for those with Caucasian hair texture. When you get a buzzcut, do you have regions that look much thinner?
SO, how hard is it to achieve this uniform density?