Why could only noble Egyptians become charioteers?

This can be explained by the fact that the chariot was very expensive. They needed horses that not everyone could afford. Thus, most of the chariots were from the nobility. At that time, chariots were considered the most formidable weapon. They made their enemies fearful. True, the chariot did not dominate for very long. Soon its place was taken by war elephants, but they turned out to be not such a perfect weapon of war, which they seemed at the very beginning.