In some fields of engineering PE is pretty nonexistent. Some people come from other degrees (like math, physics) and call themselves engineer without difficulty. But engineering fields require a much more narrow and deep set of skills. generally the key classes to learn those skills come at the end of three or four years of prerequisite classes, so it's a pretty high barrier to starting without doing the degree.

In programming you can learn your way to advanced skills while getting paid. Once you know roughly one class worth of basics there's valuable contributions you can make, at least if you are decent at figuring things out on a computer.

Hate using this preface, but, unpopular opinion follows: The issue in the US is that the word engineer has been in common use to describe technical workers for a very long time. I've had friends who were:

* Engineers (and operated trains) * Manufacturing Engineers (who were really equipment techs) * Sanitary Engineers (who were really trash truck drivers) * UX Engineers (who were really web designers) * Software engineers (programmers) * Data Engineers (kind of dba-ish, maybe) * Culinary Engineer (restaurant kitchen designer)

Genericide has occurred. The boat sailed.

When the real estate industry wanted a word for "licensed seller of property" they had to make up a new word "Realtor" and protect that with a certification mark. The engineering industry really needs to do the same thing instead of harrassing the garbage truck driver, computer programmers and the guy who fixes the conveyor belt.

This is heavily dependent on the field and state. PEs are quite rare outside civil engineering.

Not enforceable. Or at least entirely winnable in court. Such a victory happened recently in Oregon:

https://ij.org/press-release/oregon-engineer-wins-traffic-li...

TL;DR: such restrictions violate your freedom of speech.