How does a supposed mechanical engineer not know even basic things about metal or what different types of mechanical stress look like?

There’s this old engineering joke: a physicist, a chemist, and an engineer are asked to find the volume of a red ball. The physicist uses a piece of string and a ruler to measure the circumference and then does the appropriate calculations. The chemist puts the red ball into a measuring cup filled halfway with water and compares the before and after of the high water mark. The engineer consults chapter five, subsection b, table iii of the industrial guide of red balls.

Because it’s a field where you can get by, especially at the middling level, on just brute force memorization, engineers sometimes don’t think about first causes. Fundamental measurements aren’t necessary if you can just consult the specs and plug in the calculations. Same reason for the old trope of “scientists” who say they don’t believe in evolution are almost always engineers.