Economics is a factor, but I'm not sure I agree that the guys between 30-40 can be driven harder. Your comment assumes we're talking only about male engineers here, which I find interesting, but let's go with that for purposes of this discussion.
Young kids have busy lives with school, sports and other extracurriculars, and most young fathers aren't willing to miss out on being involved in their kids' lives just so they can "handle more abuse" at work.
Older engineers have grown children who are either high school age and mostly doing their own thing already, or have already reached adulthood and moved off to college or out into the world.
The older engineer with an empty nest has already done his child-raising and finds he has more time on his hands than he did when he was younger. If he is passionate about his work, wants to learn a new skill or whatever, he finally has the time to do more of it than when he was younger and had so many more family obligations.
Even on an ordinary day, without any urgent deadlines, there are still engineers in this office way past the usual dinner hour. They tend to be the older ones, who don't have to rush out the door at 5 o'clock to pick up kids from daycare.
The "wife at home" comment was good for a laugh too. How common is the male breadwinner, female homemaker scenario these days? It's not 1957 anymore...
It's easy to forget that correlation does not equal causation. I think that's at the root of a lot of age discrimination. If a younger hiring manager has seen a high percentage of older applicants not having the current required skill set, he or she may likely incorrectly assume that it's age that causes the skill deficit.
It's really not though. You can find highly skilled as well as marginally skilled individuals or any age. In my kind, the key is to keep educating yourself. The classes you took 30 years ago may be irrelevant but the ability to teach yourself is not. You can be a total hotshot PASCAL programmer on 8-bit machines, but that won't help you get a job in a C#, MVC, Visual Studio shop unless you've found a way to add those skills to your knowledge base.
Keep humble too. In the same sense that being old doesn't mean that you aren't able to do the job, being young doesn't mean that a manager or engineer can't be effective.
no-one is ever laid off or not hired because of their age - it's always for some other reason, and those are easy to invent.
Forty years ago, they could say to you "you're too old" and at least you knew where you stood. Legislation makes liars of all.
So, just over 50 of the self-selected respondents in EET's survey claimed to be both over 50 and two years out of work. When expressed that way, does it really sound so bad?
I am over 50, unemployed, and unhappy about it, but I make no inference of ageism.
In general, nobody will tell you strait in your face about your age, they are not that "rude".
They have 101 reasons to disqualify you, bottom line they are in driving seat, do not have to tell you real reason anyway.
Personally, I wouldn't want to work for a company so limited in its thinking that they practice age discrimination. I don't care about the odds because I need only one job at a time.
My advice is just the opposite of dsholland's. Study your technical material but be prepared mentally and emotionally for a layoff any millisecond. Get three books: What Color is Your Parachute?, Guerilla Marketing for Jobhunters, and Think and Grow Rich (public domain so free these days). Study all three. Get good at job search.
Never turn down any assignment offered even if it's not quite your usual line. You never know in advance what you might learn and when that will come in handy in future. I have worked in development, QA/test, technical writing, supervision, management and feel qualified to do almost anything. I am easy to manage and to work with.
Be able to move to a new city for a good job. This last year I turned down a short term contract in FL for a full time job in TX. 5 weeks into that job, I got a better offer in PA (45% more money) so I moved there. Moving in one's 60s is a challenge, but quite doable. I plan to work into my late 90s. Join Forty Plus if there is a chapter in your city.
Manage your morale (most important single task during a job search). Don't look for any job, look for your favorite job. Daydream about what you have liked and hated in prior jobs, and use TaGR to call out to that perfect job. This is what Parachute calls a life changing job search. If done correctly, you will find that wonderful job.