In the spirit of constructive discussion, I have several thoughts about why other people may not see this. One, it's quite possible this is a very locale specific phenomena.
Secondly, I have tended to work in - and therefore interview people for - very mainstream languages, I suspect the experience of someone who works in/interviews for Haskell would be very different.
Finally, it's entirely possible that most of the applicants are by definition, the ones who find it difficult to get and/or hold on to a job, and that throws out the experience of the recruiting process, and that means they make up a disproportionate number of applicants, despite being a minority of programmers in the workplace.
I have encountered them in teams that I’ve inherited, and although I don’t find that it’s the majority of applicants at interview it’s a significant proportion and you get no indication of it from other parts of the interview. I’m talking about people who struggle to work out that they need a loop.
Being able to talk about playing the piano is not the same as being able to play the piano.
My interview approach is simple - I talk to people about the things they’ve done and ask questions based on that. I discuss higher level concepts and don’t worry about syntax. I take about one hour, sometimes a little longer. I have never hired or recommended a hire of a dud.
80% of the people in this industry write CRUD apps, web apps at that, or simple API backends for said apps. Some of course create new languages and kernels, and I don’t know what an interview process needs to be for that skillset, but for 80% what I do is perfectly adequate.
When I say they cannot write code, I mean that when presented with a simple problem such as toy robot or fizzbuzz which requires them to break down a problem into steps and implement those steps, they are unable to do so.
There doesn't seem to be any particular pattern to this. I've seen it across different companies, different languages, and different seniority levels. I am at a loss as to explain if these people know they are incompetent, don't care, or are just plain desperate for some kind of work to pay the rent. Nonetheless, until we find a better way to weed out the majority of applicants who can't actually write code, this is the best option we have.