It happens. It's awkward because not only does it obviously suck for the employee but it means there's a big problem with the interview process. When I worked f

It happens. It's awkward because not only does it obviously suck for the employee but it means there's a big problem with the interview process. When I worked for a company that encountered the same problem we corrected for it by adding a screening call, after CTO chat and before an on-site. We used that call with a senior engineer to perform a trivial live-coding problem in Code Sandbox. Every candidate got the same problem, so it became our benchmark. It was a 5 minute problem, 10-15 if you're nervous in an interview. We were able to weed out not only all the candidates who couldn't solve it, but those that took 40 minutes, those that could barely find their way around a text editor, those who struggled to write syntacticly correct JS, and those who had to rely on Google to write a for loop. For those rare candidates that completed the problem rapidly, we would give them a follow-on question that was a more typical interview question, just so that they didn't think our bar was set stupidly low.