Modern companies are rubbish
How inhumane modern companies have become.
Young = cheap, older = "worthlessly" expensive, is an equation which doesn't balance. Inexperienced young people make mistakes and need to gain the learning and experience to actually be able to do their job properly.
By the time someone has gained that knowledge and experience (and a few more candles on their birthday cakes), it's only by then that they can actually do the job properly and well, and efficiently. That's exactly the wrong point to throw out skilled employees and have to start with a bunch on untrained monkeys all over again.
There's also another point. Age creeps up on all of us, even slimy personnel managers who instead use vile Orwellian terms like "human resources". In 15, 20, 25 years' time, it could be any of them who is also being cast aside. If "someone" thinks that the only useful and skilled employees are those between 25 and 40 (a total nonsense) then we need a retirement age of 40, and pensions to match. But that neither makes sense nor is going to happen.