That's because glamour models have neat and tidy bits whereas the 'normal' is different for everyone. Some girls are very embarrassed to have enlarged labia and think it needs correcting.
It's not just the clitoris. Sometimes the labia are sewn up, which causes bladder problems and in some cases the vagina stitched up too, with a minute hole left for menstruation. The girls then suffer agony, when they marry.
Steady on. The point I was trying to make, is that it isn't a religious practise. Of course it's barbaric. As a woman, I think it's revolting especially when women try to give birth and have to be cut to do so.