You'll have to source that for me, because I am not buying that
I am not going to get into a pissing contest over sources, etc. Military history is rife with examples of commanders disobeying direct orders; of units leaving superior positions for what ever the reason; of units not being able to carry out the orders they were given because they were incapable of doing so (lack of readiness, lack of experience, lack of leadership, etc)...and so on. Feel free to browse the internet at your leisure to find such instances. Whether intended or not, units in RTW that do not do exactly what you direct them to do is not unlike real battle situations. I get just as frustrated as you when directing a battle where my units behave in a wayward fashion. But I take it as a challenge. So in the words of Gunny Highway : "Improvise...Adapt".

Even if all the other cars are less to your satisfaction?
Obviously, the RTW series has enough going for it to keep you coming back for more despite your distaste for its' "bugs".