Why buses weren't used to get people out

Buses were used to ferry people to the Superdome. That was essentially the plan.

The articles point out many changes since the Ivan near miss, but the most fascinating is that New Orleans whole plan was to get people to shelters of last resort, ride out the storm and wait for the calvary.

New Orleans is in an unusual situation, compared with neighboring parishes, because more than a quarter of its residents have no personal transportation. According to the most recent census data, about 134,000 out of the city's 480,000 people are without cars.