Plenty of people outside the US, too, live in caravans for a considerable portion of the year. Go to southern Morocco or Western Sahara in the winter, and you will see many hundreds of camping cars owned by German, French, and Italian pensioners who want to spend the cold months in warm, sunny weather. If there actually were seasonal work down there, I would totally expect some portion of them to take it, since some people do feel the need to make some extra money or to do something "productive" during the day.
Some full-time RV owners publish their costs. The Russos spent about $3000 a month in fixed + variable costs when in their Class-A, but only $1200 a month when they traded it for a Class-B (RAM Pro-Master van). They seldom stay at a campground.
https://weretherussos.com/rv-living-costs-full-time-class-a-...
https://weretherussos.com/camper-van-life-costs-september-20...
If I'm being optimistic, they're engaging with a community, who actually loves the RV lifestyle, and wants opportunities like this for limited periods, so they can save up for their "next adventure". I just don't know how working 12 hour shifts while living in an RV is called an "adventure". But hey, that's marketing these days - everything should be (over)sold.
My gutfeeling tells me, that the first is more likely to be the case than the latter, which is just another bad mark in the book for Amazon...