[lttlrck]

Is having a deeper than big-O understanding of data structure truely necessary?

A mechanical engineer will have an understanding the characteristics of different screws (tensile strength, corrosion resistance, material compatibly etc) enabling them to pick the right one for the task at hand. Understanding the crystalline structure and the ability to smelt one yourself is likely out of scope and probably predefined by domains experts.

Why can’t software work like this?

[rnprince]

By the time you've memorized all the cases where a binary tree does and doesn't make sense, you might as well have just learned how they work.

[louthy]

Exactly. I'd be very wary of any professional that hadn't had the intellectual curiosity to at least understand how they work, never mind actually try to implement one.