I dunno. I can think of three ways in which an older developer might have a hard time finding a job:
(1) If someone doesn't keep up with currently relevant technology, they will find themselves without the job skills that employers are looking for, regardless of whatever other qualities they may have. This isn't ageism.
(2) If someone works at the same place for 10+ years, getting raises every year and becoming more and more valuable because of their knowledge of the innards of one or more huge codebases that are specific to that company, they're likely to have a hard time finding another job doing something different that pays as much or more. It's very easy for people to settle into a routine for many years that doesn't necessarily carry over to another job. Someone in this situation might have to take a pay cut (maybe a big one) to start from square one doing something else at another company. This is an unfortunate reality of being a software developer, but it also isn't ageism.
(3) If a really young entrepreneur is hiring for their startup, and they haven't had the life experience to develop the maturity and insight to avoid being biased towards hiring people who are just like them, it is possible that they will favor a younger developer over an older developer based on age alone. They may not even be aware that they're doing it, they might just feel like all other things being equal, the younger developer is a better fit for the company. This could be ageism sometimes, and it's very unfortunate when it is.
(1) and (2) are the perils of having a long career as a developer. Employers who don't hire someone because of these reasons are making rational hiring decisions; they're not making decisions based on being biased against someone because of their age.
I don't know how often (3) happens though. I could see it being a problem in SF, where I've heard the job market is disproportionately composed of startups. I don't think it's like that in the South Bay (at least not to the same degree), where there are tons of large and established companies that are less likely to do this.
"If someone doesn't keep up with currently relevant technology, they will find themselves without the job skills that employers are looking for, regardless of whatever other qualities they may have. This isn't ageism."
Except.... I do see younger people getting hired who don't necessarily keep up with current technology. It may just be that they're ultimately cheaper, and it's just financial. But I do suspect that older devs are held to a higher standard on this front ("what? you're still using Rails 3? luddite!")
It's not necessarily rational unless the company holds all candidates to the same standards ("current with technology", for example).
What do you think 1) really is, though? Do you think "keeping up" with 100 different mvc frameworks that do roughly the same thing is "keeping up?" That seems to be what that code phrase is usually used to mean. Are younger programmers not as easily accused of this or worse than not keeping, not knowing enough fundamentals? The whole notion of keeping up with technology change in programming contexts sometimes seem silly to me. Is it really that big of a change that you can start to do with JavaScript web apps what you could do 20 years ago?
You are right, but unfortunately some of the misinformation (or maybe it was like that in the beginning?) about the Google hiring process made it to other companies, so the hiring process focusses on a lot of detailed knowledge about Rails 4 even though you may have a ton of Rails 2 experience and after that you did 5 years of full-time Lift, you might still not get the job because you are not 'current'. I think it's rather a lot of bullshit and actually the reverse is true as well; I see programmers who learned and used a specific thing, like Rails 4 having issues picking up anything else well. Yet people hire them because they 'kept up'. Have fun with that in a few years :)
What you describe in (2) doesn't just apply to software developers. It can also apply to sysadmin/SRE-type roles. I'm what passes for an "expert" at operating a very complicated yet unremarkable piece of software used by maybe 100 companies world wide. My salary has gone up rapidly over the last 5 years mostly because of my knowledge of this niche (and near EOL) software.
My next job likely will not be using this software so I'm doing my best to keep up with what's changing in IT generally. I even schedule a time once per week to work on a side project just to make sure my development skills stay sharp-ish. Despite the effort I put in, I expect that I'll likely have to take a pay cut if (when) I go to another job at a different company.
If it sounds like I'm complaining, I'm actually not. This is just how it works I guess.
(1) If someone doesn't keep up with currently relevant technology, they will find themselves without the job skills that employers are looking for, regardless of whatever other qualities they may have. This isn't ageism.
(2) If someone works at the same place for 10+ years, getting raises every year and becoming more and more valuable because of their knowledge of the innards of one or more huge codebases that are specific to that company, they're likely to have a hard time finding another job doing something different that pays as much or more. It's very easy for people to settle into a routine for many years that doesn't necessarily carry over to another job. Someone in this situation might have to take a pay cut (maybe a big one) to start from square one doing something else at another company. This is an unfortunate reality of being a software developer, but it also isn't ageism.
(3) If a really young entrepreneur is hiring for their startup, and they haven't had the life experience to develop the maturity and insight to avoid being biased towards hiring people who are just like them, it is possible that they will favor a younger developer over an older developer based on age alone. They may not even be aware that they're doing it, they might just feel like all other things being equal, the younger developer is a better fit for the company. This could be ageism sometimes, and it's very unfortunate when it is.
(1) and (2) are the perils of having a long career as a developer. Employers who don't hire someone because of these reasons are making rational hiring decisions; they're not making decisions based on being biased against someone because of their age.
I don't know how often (3) happens though. I could see it being a problem in SF, where I've heard the job market is disproportionately composed of startups. I don't think it's like that in the South Bay (at least not to the same degree), where there are tons of large and established companies that are less likely to do this.