And why should general taxpayers have to cover the insurance of obstetricians to perform elective CS's?

It's not about who should pay what, they are taking away choice from women.
I would imagine as electives are done in a safe environment where if something goes wrong there is immediate surgical intervention, assistance and facilities on stand by including back up staff and specialists. People who elect to get plastic surgery are also privy to immediate surgical assistance and facilities for emergency intervention. Home birthing midwives don't have this.