It's also that coders tend to... err... "offload" memory for the stuff they aren't immediately using on a daily basis, and only remember the general terms and names that would be enough to find and remember the details shall they be required.

Last time I've had to do something with the trees implementation details (IIRC, that was AVL trees) was, like, 5 years ago. Right now, I don't exactly remember anything about AVL trees except for they have that nice O(log n) for lookups, insertions and deletions. Would I need to code them from scratch (or remember their internal workings for any other reason, like debugging some core dump), I'd go find the algorithm description (or particular implementation's source) and do so.

At the same time, last time I've worked with balanced trees was just a few days ago, but that was Erlang's `gb_trees` module that did all the stuff and I just had to freshen my memory on the syntax details.

All I would be able to do on a whiteboard is stare for a minute, trying to remember stuff, then probably say "uh, sorry, I don't remember this stuff - haven't did that in a long while". Yes, that makes me a worse programmer, I guess, but are interviewers actually looking for those who remember everything in their head and write code on whiteboard? Looks like a weird case to me that doesn't have to do anything with reality.