I think this is like Noah who didn’t go into the Teva till the last minute. People knew intellectually that it might happen, but couldn’t imagine it actually happening.
Preparing buses to start escaping under bombardment is not usually a recommended prudent action. We can see a difference between lack of fear when Hashem is punishing people with an invisible virus v. immediate recognition of danger when melech basar vedam starts bombing… Why not say that bombs are not real, and buses killed more people than bombs? (True)