Cool things with wheels since 2006
http://www.ewillys.com/2020/10/12/1958-photo-of-the-fc-leveloader-on-ebay/&https://www.gettyimages.com/detail/news-photo/elevator-truck-from-thompson-trailer-corp-devised-for-news-photo/50323842shows truck bed sitting on the ground. Seems to me I have seen a photo of these loading & unloading old freight airplanes, like back in the 1950s, not finding it.
My guess it's to get it up to the height of a loading ramp intended for larger trucks. Lescarp's suggestion it could be used for loading aircraft seems just as plausible.
The truck could be low and compact for getting around the city, then raise the bed up to dock height for loading and unloading.
Since there is no rear axle or driveshaft, I assume they are driving the front wheels through the transfer case?