I have been doing some research on vbac. if the percentage of uterine rupture is so low, why does it seem like doctors still do not prefer to perform them?

Uterine rupture fear: Because of the fear of uterine rupture (risk is 1 per 110-200 patients trying labor after prior c-section), the american college of obstetricians and gynecologists had recommended that vbac only be "attempted in institutions equipped to respond to emergencies", so doctors were not comfortable doing vbac in case a life-threatening emergency were to result, and some hospitals did not allow vbac's.

Risk: Many doctors still do vbac with proper council. The risk of uterine rupture is about 1% for spont. Labor, 2% for augmented labor and 4% for induced labor. This is low. The concern is the consequence of uterine rupture. 50% catastrophic results, loss of mother, loss of baby or lifetime neurological injury to baby! many but not all couples are willing to accept those risks.

Immed available: Because the consequences can be catastrophic - death or disability to both mother and child. This is why acog recommends an md be immediately available during a vbac. Since most obstreticians can't be in the hospital 24/7, most prudently decline to vbac. If you have a obgyn who can commit and you are an appropriate candidate, vbac's can be highly successful.

Liability concerns.: Although the absolute risk for uterine rupture after one prior kerr cesarean section is 1/200, that risk increases with short inter-pregnancy interval, more than once prior cesarean, non-kerr prior c-section, induced labor and likely with multifetal pregnancy (not clear). Also, if this occurs the outcome is potentially lethal for fetus and/or mother, so you can imagine why it is not appealing.