The amount of times I've heard interviewers go "Oh I had this super experienced guy who but in the interview he couldn't even do some simple programming problem". To me that is a failure in the interview process. I've seen this when I've interviewed people. If people don't do well when their resume implies that they should, I'll discuss it with them and say we want to get some kind of confidence in their abilities. Then work out a way to do that. This has worked out really well in my experience. I've ended up with devs who are quite different from me, one person of note (who we employed), was much slower at solving problems but far far more methodical and exhaustive in approaching problems and often notices very subtle details (which is a good thing in firmware development!).
The only way I could see that scenario could ever occur is if the candidate outright lied on his resume. A quick solution is to check references (call the school said person graduated from, call references, call references via their company line, etc).
Sounds like the interviewer didn't bother checking references.
The majority of shops that firmware devs come from (and particularly defense) have a policy of only verifying the dates of employment and nothing else.
References would be personal references - someone with a cell number and call the college he attended; they should also verify enrollment and completion. You don't want to be calling the HR department. Also, a secret is if the reference (not HR) only verifies employment, that's a negative review. They are concerned about liability. If it was a good employee, the references have no qualms about saying so; it's the negative aspects that carry legal liability.
You need to ask for those, not just prior companies. My resume has a "References available upon request" at the bottom and I'd happily give them. Is that no longer practiced? It used to be a requirement.
