In this question lies one of life's mysteries. If my family were in this race, my wife and son would have to do all the driving because neither one of them, and they are both very bright, can read a map. I would have to do all of it. I too can't understand what the problem is, but some just don't get it!
Note to all you dads out there: teach your kids to read maps at an early age. They'll catch on quickly and thank you for the rest of their lives.
My dad did me that favor when I was so little, my feet couldn't reach the floorboards. Popped me in the front seat, handed me the map, and explained how to use it. Thanks to his efforts, I'm one of those rare grrrrrrrls who have an unerring sense of direction. (And I think TAR is going south.)