Older adults not being hired for new jobs, being eased out of old ones because they are perceived as too rigid or feeble-minded, and being eased out because they are not considered cost effective are examples of:

It's an example of Ageism.
Eventhough it's true that older workers tend to work less if seen from the working-hours point of view,
But, the studies show that they could be as capable as the younger ones because they posses more experience which makes their working hour more efficient.