Basically, any test that involves binary trees (sorry - "btree" is a somewhat different thing).

Realistically, most programmers never see another binary tree, after they leave school.

It's a "youth-pass filter." People right out of college will ace them. Us oldsters are less likely to do as well (unless we cram for them). In forty years of programming, I never encountered a single one, in the wild, and a lot of our image processing algorithms involved a decent amount of data crawling, so they had some relation to binary trees (shows why they teach them), but the way they were handled was much different.