Why people or country think that 60 yrs is retirement .When a person is healthy and capable & with experience he can perform better then why cut off?

If youngsters wants to lean from Experienced person. Senior people like us has to be Employed with

Juniors. Then only you can learn from our experience  

Normally people think when a person turns yrs he/she cant be productive and then it is better to concentrate on youth who are more active and productive. On the other hand, when a person turns yrs he/she have to pay effort and teach yougsters along with their career !