Is it normal for a bride to choose how bridesmaids wear their hair for the wedding ceremony?
It is your head. You are free to do what you want with it.
If a bride is demanding a certain style that can't be achieved without help then I believe the bride should pay for styling.
I understand where the bride is coming from if she doesn't want one girl showing up with an elaborate up do and another with her hair down. It all really depends on the bride's personal vision (ha, most just raid board on pinterest and instagram channels!) and of course the hair lengths of the bridesmaids! If the bride does it like she should the girls should talk among each other, instead of dictate, the girls do what they want at their own expense.
Next she will pick out your underwear.