Back then, you could do things more freely with less capable and available hardware. Different environment. Concept of computers was scratching the surface of what they could do for us, and people didn't have a notion of liabilities. And yes, the student didn't install the HVAC systems, but how did tele-operated harwdware interface with it? They didn't have echo dots and knockoff power plugs back then.
Today, you have all that available hardware but can't realistically do things as freely. Suffice it to say that the environment has clammed up on all fronts for an amateur to enter an industry. In some cases rightfully so (only experts for surgeries, plumbing and wiring for me please). In others, egregiously wrong barriers. For example, commonly the first thing that happens in a public institution or agency is that the losing bidder files FOIA requests trying to litigate why their solution was passed up and by whom, including copies of correspondence between them. Imagine having to deal with that dimension.
Back to traffic lights: for something so rudimentary yet so vital, it costs millions of dollars for a handful of intersections, and they're everywhere. Nearly a prime candidate for a four raspberry pi solution, right? You'd think someone would have attempted it.