There were also locking ones, usually using a cylindrical key. My Mustang got a set of those around 1971 after it was stolen twice in one week. The underside of the hood still has the patches where they were removed a couple of decades later.
I don’t really see a good explanation of the pins/cables - they came into use in racing, mostly drag racing, for both fast access to the engine compartment and double security to hold the hood in place at high speeds. Cars of this era were about as aerodynamic as a brick and the underside pressure on the hood at 100+ MPH could blow a hood fifty feet in the air.
Similar pins with flip-over ring cotter pins were used in at least one or two prior generations of racing to hold various body parts on the stock and SCCA racers of the 1950s, maybe earlier. The drag racers borrowed them, and then Detroit stole them as part of glam packages for the muscle cars.