When I first learned to drive a big truck, the first lesson on the road was ' when climbing a hill, screw the rest of the gauges...watch the pyro ! '
Yes lots of trucks come without them.
I worked for one truck company , the boss bought about ten new trucks and ordered them with the bare bones gauge set. When we asked him why he didn't get gauges, he grumbled " damn drivers won't look at them anyway" And he was right, alot of people won't pay any attention to the things on somebody elses truck......and a whole bunch of new pickups are purchased for company fleet use. The added cost of a single gauge on 10 , 50, 100 or more units will make the difference in making a fleet sale( if the market for pickups were primarily private users, they wouldn't build them to last so long , and they would obsolete the parts after ten years like they do on cars)
When I had my own big truck, an old Kenworth, that puppy had 22 gauges on it. I knew exactly what was going on in each part of that engine..and i worked that thing hard....of course trying to train relief drivers with all those gauges was a chore
------Robert