One of the worst examples was Amazon. They gave no indication ahead of time, but I was presented with a coding test with only a small subset of languages. My chosen language was F# because that's what I was most comfortable with but of course it was unsupported in their online tool. I solved a problem using discriminated unions, pattern matching, and pipelines. The interviewers were very confused, a bit antagonistic that I'd choose anything other than Java (even though no one told me ahead of time that there was a limited selection), and proceeded to show their lack of knowledge. For example, the interviewer kept bringing up a violation of the open-closed principle in my code. However, as I explained to them, that principle is only really applicable to object-oriented code. Since I was using a union data structure and pattern matching, that principle is not really applicable, as the functional approach is a transpose of sorts from the OOP approach. But I just got blank stares and an automatic deflation in the room of the interviewers communicating that they were ready for the interview to end. What was mind-blowing about it is that my resume lists nothing but functional oriented programming languages, with not a single example of Java, and I have plenty of code examples posted. But yet, I get asked some dumb question about reading a file using some terrible online coding platform.