Why most jobs took a smallest ages with less experiance. Beside that, we found many in old age and have more experiance and need a job?

Young people with no experience are paid much less, that's why !!!

Sure it's for the small paychecks but I think it's a great economy's problem in general. The age factor is something that you can't do anything about. If a job requries better English for instance you will get some lessons. But if they need a younger candidate you can't do anything about. This is very disturbing and surely for us (over40) it's a big problem because we are considered to be very old to work but very young to retire! 

some companies do that because usually new employees with less experience are less paid than older ones with more experience. but these companies usually forget the cost and time needed until the young employees gain enough experince to be able to do their work in good way and once they gain the skills and experience they will ask for salary increase and if you dont pay then they will go to someone else who will give them more then you have to search for new inexperienced young employees to start training them again and so on.

so it was said that the cost of training new employees is higher than the cost of mentaining of the old or recent ones!!

some compnies need new young employees because they need new blood and the vigor of the youth

i would say any company need to balance between the older people wisdom and experience and the young people youth and new ideas

Because it is not only the formal qualifications and experience that contribute to the success. There are many other capabilities that play effective role in climbing up the ladder of success