> parking lots full of empty school buses and claimed he had no way to evacuate citizens
That just sounds like a sensational headline lacking in context and details. For example, with Hurricane Harvey in Houston they had to weigh calling mass evacuation against the ability of the road system to handle that much traffic. It doesn't matter how many buses you have in a parking lot if they can't leave the city. I'm not saying that was the case in New Orleans, but I'm certainly not going to assume the worst from "parking lots full of empty school buses".
Honestly, is there even a known good example of how the response to Katrina should have been? Most people's complaints about it seem so shallow in their analysis as to appear a projection of their distaste for the Bush administration or the local politicians; nearly 15 years later.
Edit: Could you imagine an NTSB report on an airplane crash: "Air traffic control had three empty runways but said they had no way to land the plane! If they hadn't just whined and wrung their hands, perhaps everybody would have survived that flight.."