[Personal] Why respect the elderly?

My wife had a minor accident in a car park today. She parked the car and went into McDonald to get some food. Prior to going in she saw an elderly couple attempt to park next to our car. When she returned to the car from McDonald she saw a scratch on our side rubber panel, and there was some rubber debris on the bumper of the old couple's car as well. She waited for the couple to come out and told them of the incident. If the couple had just acknowledged the incident and apologized then it would be the end of that. My wife wasn't looking for any monetary compensation since it was a small scratch and the insurance claim would be more hassle than its worth. Unfortunately the old female refused to accept the facts but instead insisted that the rubber debris was "dust". No choice, my wife called the police. And the police straight away said it's the old couple's fault.

All my life I was taught to respect the elderly, I guess supposedly for their wisdom and knowledge. Well, wisdom and knowledge does not lead to doing the right things. Perhaps the more a person knows about everything, the more he/she knows how to act unscrupulously to get what he/she wants. So my question is, why should I respect the elderly? Respect should be earned, regardless of age. Unfortunately some old people tend to abuse their elderly status and use that as excuses.

In the end my wife insisted on an apology from the old lady (who was touching up on her makeup while the police was running vehicle checks) and eventually got a reluctant version after some convincing from her husband. I feel sorry for the old man.