> Isn't that the kind of thing that someone senior would typically look up?
Not at all. There's at least two ways to do this very easily in Go(one line, no errors to worry about even), and I'd expect someone who claims to use it daily to know one of them offhand.
While I think languages are just tools, in our instance we're very clear we need people versed and ready to start.
I don't think people are dumb here, I think they just blatantly lie on their resumes.