That's not unusual in aviation because of driving laws. General Yeager probably knew how to drive, but was unlicensed, the same situation with my son, "Ace." He had to ride his bike to the airport to "solo." He had not completed the academic requirements yet.
He grew up dirt poor in West Virginia, so it’s possible he wasn’t around vehicles, but it would be interesting to know for sure. Fascinating that our country lept forward in technology so fast during Yeager’s life that we went from using animals for most of our transportation needs to flying many times faster than the speed of sound, and then created rockets to shoot us to the moon.