Devils advocate here as I have given numerous interviews where we have had to give technical questions.

None of the interviews I gave was a pass/fail on the technical question.

The purpose is to gauge the level of skills the applicant has.

Even experts will look at stack overflow, but it is how the applicant approaches the question tells you more than if they are right or wrong.

Someone who has been working with a language/library for a long time building models would know the most common methods/syntax.

So if an applicant claimed they were an expert at pandas, then not knowing those commands would work against them.

The fact they gave applicants access to the documentation means they were taking people of different skill levels.

I would also recommend to be wary about talking about grabbing code from Stack Overflow in an interview. Some job roles require compliance on code source. Saying you pull stuff from SO could disqualify you immediately.

...

My point is, just because there is a technical question don't assume it's a BS interview, and that you will fail just because you don't know the answer straightaway.