@lanx0003 - no argument intended. Just pointing out my experience that degreed engineers in some industeries are not required to carry professional licensure to perform engineering work. I have seen this mostly with clients I have worked with in manufacturing industries (automotive, drug, food, etc.) but I would not be surprised that it could apply to @erik_squires for work with motion picture audio equipment, electrical/mechanical equipment, and installation.
It becomes murkier when folks who perform engineering type activities are referred to as "engineers" whether they have a degree or not. I typically roll with that one as long as their work is not encroaching on areas where licensure is a requirement. During college, I worked with an AE firm that had undegreed mechanical and electrical designers/drafters who were sometimes called "engineers". They worked under the direction of a PE who would seal the drawings. The industry seems to understand that a team of people are necessary to complete most projects and that not all are going to have a degree and registration, but those in responsible charge must have them.
A PE is absolutely required for engineers designing public works and structures, which is what I did for over 40 years (and still consult from my retirement) so I am currently registered in several states. However, @thecarpathian makes a good point - I am clearly not qualified to operate a train 