I'm surprised C-section rates are higher among wealthier, education women. I would assume educated women are more likely to understand the risks associated with C-sections.
Just because they are wealthier or educated, doesn't mean they will make the most scientific decision; otherwise no doctor would ever smoke. Background/nurturing/societal norms also play a role. I have heard multiple well-off/educated women say, "no way I would put myself through so much pain when I can have quick c-section". Note that I'm not passing any judgement as it is their body and they are the one who will experience the pain so it is their decision.
Highrr age of mother during first childbirth and money probably make difference.
Heads of their babies are larger, while vagina is same, so higher risk to rip vagina and die, so higher C-section rate.
It's not the size of the vagina that's the issue, it's the size of the pelvis. The vagina is extremely flexible. Bones much less so.