I am in my mid 50s and each year we go through the annual re-organization shuffle where they layoff people and then 3 months later hire the same number or more. The people laid off include some under-performers but most are people that come to work, do a solid job, and go home.
While every layoff requires an employer to provide an age (and possibly gender) breakdown of those laid off to attempt to disprove any allegations of age discrimination, we know it happens.
Employers are under the impression that older workers are less effective, less "up to date" with the latest technology and methods, are too expensive because they are at the higher end of their pay bands, have the highest range of benefits including vacation and may just start having some health issues including taking time off from work as well as using health care.
Some of that around health care is not unwarranted. But I suggest that often the employee with years of experience makes better decisions, has deeper insight into problems and solutions, etc.
In my industry I started out when much of the "information work" was manual. Most of it is automated today but when something goes wrong, the younger workers have no idea how the whole system works or how to go about solving a problem manually.
There is value in older workers. I have nothing against younger workers and suggest we need to allow people to retire so younger workers can find employment. One issue today is the situation where people stay in jobs even when they could otherwise afford to retire, or want to retire, simply because they need their health insurance until they are eligible for Medicare.
It is a sick society that holds people in a job simply because of the need for affordable health insurance.