Why do the pharynx, esophagus, anus, and vagina have the same epithelial organization?

The answer is All these regions are subject to mechanical trauma and abrasion.

All of the organs have role in the protection, makes them prone to mechanical trauma and abrasion. Pharynx or windpipe is delivering air to the lungs. Esophagus and anus will have close contact with food. Vagina have to endure a high intensity mechanical trauma in sexual intercourse and delivering the offspring.