think about it,
in a van your just a steering wheel holder, on a flat you work with the load, secure, tarp, etc. quite physical. can be dirty. but at the end of the day after a shower one does feel quite accomplished.
also no dealing with docks and lumpers, and when a flatbed pulls in to unoad, they are quite happy to see you. i would never roll a box again. different as night and day.
flat bedders do it better. plain, simple fact.