This isn't trivia. Creating a new thread is expensive; so understanding the difference can make a huge difference in performance.

Saying "I can google this if I need to" is a cop-out: Yes, you can google if if you realize that it matters, but if you don't know the answer you're probably not going to realize that it matters.

I see what you're saying, but in practice I see no correlation between people with great recall of arcane functions and syntax and good developers.

And the question wasn't, "What's the difference between pulling a thread from the pool and spinning up a new one?" That's a pretty good question, if you're going to be doing programming with threads.

I don't have any meaningful statistics on this myself, but I always found this passage from The Jargon File interesting:

Another trait is probably even more important: the ability to mentally absorb, retain, and reference large amounts of ‘meaningless’ detail, trusting to later experience to give it context and meaning. A person of merely average analytical intelligence who has this trait can become an effective hacker, but a creative genius who lacks it will swiftly find himself outdistanced by people who routinely upload the contents of thick reference manuals into their brains.

The cost of someone trying to upload huge quantities of trivia is a failure to update when systems change. Consider the cost of creating and maintaining high quality comments vs readable code.

So I'll assume, since you think that "I can google this" is a cop-out, that you never hit up Google in real life to look up some obscure technical point about a function that you need to call once every couple months in your coding? You know every interface and implementation detail for every standard library call in your language of choice?

I call shenanigans.

In our profession trivia is useful and even extremely important to be able to keep in your head; however, it's all but useless as an interview filter unless it's highly targeted to a topic that the job description requires expert knowledge of.