Yes, these things can all be done by amateurs. By tinkerers. We all here know it. We've done it. You've done it. Simple devices with telemetry and some logic. Simple programs that do complex things in the aggregate. Take it to your back yard, and either one of us or a highschool student could make a traffic light cheaper than $250,000 - $500,000 per intersection (WA state estimate). But neither one of us could build, install and maintain a quarter million of them, and I think you'd be hard-pressed to mobilize an army of nerds to make it scalable.
Yeah, for all we know a PE was involved in oversight of the project. That's an unknown that TV reporters didn't dig into and should have, because I think the story would discover a much more relaxed time.
But if one wasn't involved, I'm saying it took faith on behalf of the administration to assume responsibility for risk in backing this project, whether consciously considered or not. And there are risks with electrical projects beyond the computers, namely things catching on fire. What were the safeguards here? What if a logic error burned out a fan? What if someone hesitated to use the radios during a regular comm window out of habit and there was a medical emergency?
Faith here was well-founded because obviously nothing burned down and no one died. But who today would accept that risk without going to a licensed professional?