[thu2111]

It's quite common but how common depends a lot on where you get your candidate stream from. In my experience it's never to do with stage fright. The candidates don't seem flustered. They just cannot program. Even if it was stage fright, so what? Instant no hire. Your work will be evaluated by people post-hiring too: you have to be able to perform the job you are hired for when asked to do so. Panicking the moment you're asked to do your job is an excellent indicator you should not be in the team.

At my current firm, I hired most of the engineering team. In the early days we relied heavily on website applications and external agencies. A non-trivial number of candidates would struggle with a task like "read a text file into memory and print out the lines". Not FizzBuzz, if anything that's even easier: FizzBuzz trips up some inexperienced candidates because they don't know about the modulo operator, which is relatively rarely used. But almost any kind of program will use files.

At some point we started pulling sourcing and recruiting in-house. We also dropped some bad agencies and got a bit more savvy about which ones were cheating. The candidate stream got better at that point and total failure became less common. Unacceptably poor performance was still a frequent issue though.

Disappointingly, to me, a lot of candidates and even people we hired would try to claim that asking candidates to load a text file from disk was somehow unfair because "real programmers" don't work with files anymore, they just use web frameworks to do everything. Needless to say, that was not the kind of software engineer we were trying to hire.