You have to take into consideration of all the different exterior add ons that these types of vehicles have.
Ladders, racks on sides and tops, light bars, larger rear bumpers with attachments and more.
Are they all secured tightly so they won’t be pulled off or blown off at the blowers?
Also what type of dirt/film are on vehicles, cement dust, paint, oil, rock among others?
Sure you could probably wash most of it off but at what cost. I would not want to be the next car in line.
All the crap would get into all of your brushes, ceiling, floors, pit and walls causing A LOT of issues.
Sounds like I’m describing pickups
It’s hard enough washing pickups when they come in with God knows what in the backends.