They can definitely ask a complicated problem. On-sites are 4 hours long these days.
The ability to understand the underlying need behind a request is important to being a good employee. If a candidate fails completely to understand the purpose of a question during an interview, and in fact continues to argue against you as you explain it, they aren't a good candidate at all.
I agree with everything you've said, but that still makes it a bad and equally obtuse question. If they don't actually need a CSV parser, they don't need to know that you can parse CSVs, either (if you can - which is the other point - you might be a pretty good programmer if you can quickly parse a CSV, but there are tons of excellent programmers who can't).
And that was when I found out parsing something that should be as stupid simple as CSV file can actually be pretty complicated.
I understood the "purpose" of the question and I self-selected myself out of a role I would've been bored, micromanaged at, and probably not challenged at.
I’ll take someone who gives an idiomatic answer over someone who reinvents the wheel anyday. Who is likely to be more productive on the job?
Overgeneralized at best, LOLworthy at worst. Does this include palindrome questions for Ruby that require the use of linked lists? Because I had that from a CTO of a couple-hundred person company not two months ago.
They can't ask you a complicated problem, because they don't have the time (nor do you) to solve a real problem that requires coding.
You are totally missing the point of what they are trying to ask you if you insist on using pandas for parsing CSV. Understanding the point of what you are being asked to do is critical to being a professional software developer.