Once upon a time, in a village in a faraway land, there was a doctor, Dr David. Dr David was an expert in herbal treatment. He stored many herbs in his clinic and sold them to villagers who sought his consultation.
One day 2 villagers confronted Dr David and accused him of price discrimination. The 2 of them had a fever a few days ago, and had consulted the doctor. They had recovered, and while chatting in the fields, discovered that Dr David had charged them differently. Of course the one who was charged more was unhappy and dragged the other fellow to confront Dr David.
Looking at their medical records, Dr David explained, “His fever was caused by throat infection, thus I sold him herbs that can soothe the throat.”
Turning to the other, he continued, “Your fever was caused by the wound infection on your arm, thus I sold you herbs to apply on the wound.”
“Different causes for fever, so different herbs were used, thus different fees were charged. It is my responsibility to find out the root cause of your illness, and use the correct herbs for treatment. Herbs, when used wrongly, can cause death.”