People are strange. I can totally picture someone who is an experienced senior, a hero under the pressure of a critical production outage, yet whose brain goes into a crash loop when sitting across from someone who has the power to deny them their dream job.

Not claiming to be that hero, but I have personally had those moments where I came out of the interview, and as the disorienting fog of pressure lifted during my drive home I said to myself, "WTF happened to my brain in there? I know that stuff cold!"

EDIT: I think I read this one from a commenter here, but it's so true: We're interviewing people to be music composers, but judging them by their ability to be performance artists.

Fair enough. I certainly don't claim to know the best interview method ever; simply that, in my experience, starting with trivial coding questions has a higher benefit/risk ratio then other approaches.

I don't agree. They should be able to write that as a solution to resolve an issue. It should be very well understood why they're writing it. Additionally, if you want to keep going under that justification: you should also accept quick alternatives that aren't the naive approach.

(i.e. bring out groovy, using bash, etc)

Even a "systems" language like Go is just as suitable for a "quick alternative" as a "scripty" language like Apache Groovy or Bash.