This is what I drive and two reasons come to my mind.
1. Its the perception of the by stander. Unlike Ford and GM the RAM mirrors look different when extened (vertical) than when retracted (horizontal). The incidence of unneccessary mirror extention for Fords and GMs may be no less than Ram. Its just not as obvious to those outside the truck (i.e. the by stander).
2. Electric versus manual. Unlike Ford (many-not all) the RAM mirrors are a manual extend. Result, the driver doesn't take notice that the mirros are unneccessarily extended until after getting in truck and driving down the road. If driver is in Ford he can retract while driving, but being in the Ram, and without a passanger with more musle than my wife, he can either retact the Driver's side and leave Passanger side as is, thus looking like a dork, or say to himself "I need to remember to put those away the next time I stop". After a few weeks He remembers to do that.