I suspect the reason for seeing so many motorcycle jocks in the vehicles has to do with "track vision". Those of you who race, or have raced bikes, know that the key to winning is the ability to avoid problems created by the track. That kind of vision comes from experience and those who have raced cross country/enduro/motocross have a well developed sense of where unseen problems are.
I am enjoying this thread quite a bit. My days in the woods with a rally car go back to the era of Satch Carlson and NO, there were no young girls used or abused.