Yup, people who design and develop cars and aeroplanes and railway trains and weapons typically don't become PEs, and if they do, typically their employer will ask them not to put it on their business card. The reason is that PE is largely a jobs for the boys trade restriction act these days, although it is fair to say there was an element of usefulness way back when.
Specifically the PE exam requires fairly little intellectual effort, it is open book, and the codes are not impossible to understand even on a first reading. just for fun I did a practice paper on the design of wooden structures, a subject in which my life experience and learning has been limited to building a shed. I studied the code, answered the questions. And passed.