And you have to remember that FEMA response to Katrina was so scattershot that many of those trailers sat unused in lots as far away as Hope, Arkansas, rotting away in the heat and humidity for months on end before they were ever delivered, if they were delivered at all.
Aside from that, you’re entirely correct. I helped someone buy a used motorhome a few years back and did a lot of research to prepare for it. One thing I learned is that even the 6-figure rigs are often parked in a storage lot somewhere and ignored except for one or two weeks a year. A roof leak develops in September, and no one notices until they pull it out of storage in May. Then they scrub off the visible mold, Febreeze the inside, and try to dump it before the structural damage becomes apparent.
RVs require constant maintenance and even people who only have them as actual recreational vehicles often neglect them scandalously.