Earlier quoted context omitted.
A Medical Doctor must have specific training to not harm their patients. An Engineer designs functional things. No reasonable person is going to think that him calling himself an "Electrical Engineer", which he is, construes that he had specific training in designing traffic infrastructure that doesn't accidentally harm people. Traffic infrastructure is not a nuanced topic full of dangerous pitfalls. He was claiming…
I very much disagree with you. While traffic engineering failures may not be as acute as a medical doctor, the effects can be much more expensive and far reaching. For example, let us say that a road has a design speed of 55 mph. That would dictate the maximum curvature of the horizontal alignment. If an engineer chooses to ignore this design speed and makes the corner too tight, there will likely be a crash cluster…
You don't.
"Engineer" is not broadly considered a claim of authority. It is a claim of knowledge.
If I am required to provide credentials whenever I say "engineer", then how, as someone without credentials, am I supposed to express my background?
I'll simply choose another word, which will have the exact meaning that "engineer" currently does. Why? Because you redefined the word.
The word "engineer" is perfectly adequate in its current state.
If you really want to know whether you can trust an engineer in his or her capacity, you will then ask for some credentials, like a degree or state-sponsored license. The fact that anyone can use the word "engineer" to describe him or herself does not in any way detract from that.
The reason that MD, EMT, or police officer are different is that every individual who claims that title is treated with authority.