I would venture to guess that this is because certain things DO carry higher risks. The increase may be small, but it still is an increase. When you have a board of midwives who make all the rules, it becomes very bad for the women they serve. If a midwife has a high risk patient, that patient should be transferred to OB care. Don't people on here say Dr's are for high risk women??
Yes, certain things do carry higher risks. If a board of primarily midwives was used, that is not to say that they would assign or have any desire to assign high risk patients to CPMs. They want to perform within the scope of their practice, not to put women at risk. The issue is that boards of physicians are labeling many women high risk where high risk does not exist, and that "high risk" is sometimes subjective. Remember that physicians are losing patients to midwives and have a vested (egotistical, if not decidedly economic) interest in preserving patients for themselves.
Personally, I would be very supportive of a board that was composed of equal numbers of physicians and midwives. I think in a place where CPMs are licensed and regulated and continuing education crosses professional borders, there is an environment of respect for the different emphases of the many professions who have a role in childbirth.
I am sorry to hear what has happened to Amy. Though I haven't had a homebirth in NC, her name gets around as a professional and one who many women praise after their births. I can't imagine a higher form of praise and I hope Amy is released and what has happened sparks the right sort of debate in NC to allow CPMs the recognition they deserve as providers.