Some people should not be allowed to drive anything bigger than a lawn tractor.  If you really want to get scared....to drive a full length 5th RV trailer behind a 1 ton dually pickup, all you generally need is a regular driver's license.  And in some states.... tow a boat behind that rig.
In 1983, I was working in a cherry packing plant, which sent a load of frozen fruit south.  The sign on the freeway said clearance 13' 8".  The trailer measured between 13' 2" and 13" 4".  Unfortunately, the state's hired contractor had simply laid down something like 6+" of asphalt, and didn't mill anything off first.  That cost the state a fortune when the measuring tapes came out and found out that it didn't meet federal regulations.  The trailer rig came to a screaming halt wedged under the bridge (53' trailer,) from 60+ mph.