No price reduction for bald head haircuts?

Why is that no barber shops or hair stylish businesses don't offer a reduced price for people with no hair on top.  All the prices show what to expect for hair styling, hair cuts, shampoo, perms, coloring, etc.  Why not a reduced price for those of us that don't have any hair on top. 

Most haircuts average about ten dollars are more for a complete cut. What about a non complete cut? 

When I get my hair cut at a barber or other hair cutting facility, if I sit in the chair at the same time as another customer, with a full head of hair, and the stylist or barber starts at the same time I am usually finished well before the other person.  So the person that cuts your hair gets paid $10 for one hair cut and they can cut 3 heads per hour or $30.  Now consider a reduced price of say $8 for bald heads.  At $8 per head and the person can cut 5 heads per hour that equals to $40.  That is an extra $10 per hour. 

Where is the logic on charging the same for all heads of hair.