To me there is nothing wrong with living in a mobile home until you can line up the cash you want for a house --- mobile homes can be sensible --- and anyone who can buy land near the coast could certainly afford land further inland if they chose. You don't have to put a mobile home near the beach if it's your permanent home.
A lot of the folks living in those mobile home parks are elderly, too. Some very elderly. And some of them may have been too frightened and /or incapable of leaving without assistance from someone else. John Zarrella on CNN was talking about a group of elderly physically unharmed but dazed. They'd stayed put, and the building they were in was so badly damaged that it was immediately condemned.