Liability. Aside from the fact that none of us want to be in a situation where there is a serious complication with mom and/or baby and appropriate facilities are not readily available, any bad result is grounds for a lawsuit and liability coverage is either not available or very expensive. Fix the liability system and i think you will find the medical establishment more accepting.
Knowledge. A couple approaching childbirth has a limited knowledge base, preferring the "never would happen to me" approach.Some think that if problems arose they could just call an ambulance and things would be fine.They are unaware of the precious minutes lost that may mean a dead or injured baby. I, like many docs have seen far too many "normal" pregnancies with scary outcomes.