Because it’s inevitable, please withhold judgement on the Louisianans who didn’t evacuate before the hurricane if you’ve never had to make that decision. Evacuation is often better but not easy.

Evacuation requires time; the roads get backed up for hours. Evacuation requires money; it’s like taking an unscheduled, terrible vacation. Evacuation requires a place to go; not everyone has family & friends inland, hotels book up, and you have to find a place for pets.

You often have to have that money often in cash because credit and debit card readers are useless when the electricity goes out during a storm. It can take days (or weeks in really bad cases, years for Puerto Rico) for all the utilities to be restored.

As some others have brought up in the responses, evacuation also requires a means of transportation that not everyone has. I’m sure there are other considerations worth mentioning specifically that I’m forgetting; feel free to add them in the comments.