once a cesarean is not always a cesarean

As many of you know, I have had two vbacs, vaginal birth after cesarean.  These births were life changing for me.  My body DID know how to give birth!  When I was 34 weeks pregnant with my son, my first vbac, my OB/GYN  sent me a three page typed letter detailing the dangers of a vbac.  THREE PAGES!  He then proceeded to tell me that he would not attend the birth of my child.  Lo and behold, it took me 6 minutes to push my son out, no tearing, no complications!  Why are doctors so scared of vbac?  If a patient is truly set on a vbac, why doesn't the doctor transfer her to a midwife??