That's the $64,000 question. If I knew the answer, that would be my startup. It's a tough problem. It almost makes one beg for some sort of one-off certification (bar exam?) so we can put that to rest for ever after. I'll go out on a limb and say that most lawyers, especially the senior ones, probably couldn't pass the bar exam again. Developers have a mini bar exam every time they interview (hence the studying).

That said, there's one thing you wrote I took interest in: "I've met lots of folks who talk a great game, have all kinds of experience listed on their resume, and yet somehow can't write up a linked list..."

Umm...that would be me. I've never written a linked list. Guilty as charged. Java has a LinkedList class and I've never bothered to look at the implementation nor have I ever been curious enough to (re)write one from scratch.

I wish you would have said "...and yet somehow don't know when to use a linked list." That moves it from an academic exercise mostly applicable to CS students who might have written one 6 months ago, to a meaningful real world scenario and more than legitimate. Choosing the appropriate data structure, knowing when and why, is both realistic and important. I don't know how a candidate can bullshit their way thru a discussion of data structures where they can articulate, accurately, which one to use, when, and why.