Shellbelle - one thing you're overlooking is that OB's are specialists in complications, not normal pregnancy, and in my wildest dreams I would never advocate that anyone having a normal birth go to an OB just because they have PHI...it's a statistically great way to have a normal birth become a complicated one. This is not bias, this is clearly illustrated in the figures from the past two years, that came out recently.
For the sake of the wellbeing of mother and child, it would be cheaper to cover midwifery with PHI, instead of sending them to OB's when there is low risk. Why would I go to an orthodontist when I just want a check-up that a dentist could give me? Well, there IS one reason...I'd probably get an orthodontist appointment sooner ...