Supply and demand curves _ALWAYS_ meet. It's just that the point where they meet tells you what the market-clearing price is.
Sometimes this information makes one sad.
Managers who "can't hire good people" are sad because good people cost more than they want to pay.
Employees who "can't find a job" are sad because jobs that match their skills and other requirements pay less than they want to receive.
Nifty little device to make a an important point.
I'm an attorney specializing in compliance and privacy, so most all of my work is 'consulting'. But I run into companies every day who enjoy being constantly understaffed. It's the fashion in IT atm. A company without dozens of open positions isnt considered 'lean' and so they keep many open just so they can say they are there. (Some hr depts probably also think open positions are a headge against downsizing. They arent.)
How exactly? The author has not provided (and neither have you) any examples of how age discrimination has affected him except through vague feelings.
On the other hand, in the story alone, it's already been demonstrated that he's not really resilient in the face of adversity. Just because he gets rejected from an interview, he stops looking for a job for a few weeks? That sort of attitude will get you nowhere, no matter where you are.
What they usually mean is "they can't find an employee in the location they want, with the credentials they want, with the skills they want, at the salary they want, who's been trained by someone else."
This is a highly overconstrained search. If/when employers loosen one or more of these constraints, candidates show right up.
Like everyone, I prefer to get exactly what I want.
...but it doesn't always play out that way.
When I've needed staff and my dream candidate isn't there, I've hired imperfect people that I had to train, raise the rate I was willing to pay, put together attractive relocation packages, etc., and I've never had a problem hiring in 20 years as a manager.
(Both parties in an employment relationship may not have equal bargaining power, but I take issue with the implication that employers have no agency and workers no power.)
EDIT: A point I wanted to include or imply, but couldn't really shoehorn into this inversion, is that just as employers set bounds on what they offer employees, workers set bounds on what offers they accept. Sometimes it's rational to hold out for the right role through an extended period of unemployment (while focusing instead on finding the right role and acquiring or sharpening marketable skills) than to take underemployment that leaves you with no time for improving your position.