Seems awfully unusual that a truck would announce its appearance with an ice cream truck jingle. Then you remember children are most likely to come running at the sound of an ice cream truck's music. The bloody front end of the truck only reinforces this.
While we get some scenes showing the wider disaster at play (the bridge and suburb scenes, mainly), we don't really get too clear an image of just how widespread the situation really is. Given the technology/machine-dependent state of the world even in 1987, if all the machinery of the world were to come alive and turn homicidal then "catastrophic" would not be an exaggeration. There's a reason the main page describes the film as "Night Of The Living DeadWith Trucks".
Talking of which, imagine the death toll in a modern factory, the machinery in which could easily mangle a human in seconds and come back for seconds.
What if the film were to remade today? With the proliferation of cell phones, the machines could score an instant, near-total extermination by just having all the cellulars of the world electrocute their owners (or overheat and explode, depending on the machine's capabilities.) Incidentally, King himself would later write a novel about a cell phone apocalypse.
For that matter, the tech-driven state of the world also means that there is virtually no place you could go to get away. If you leave cover to go out into the streets, you're a target for cars. If you hide in the shed/garage, the lawnmower or trimmer will come after you. If you stay in your home, you're at the mercy of your appliances and personal devices, even such innocuous things as radios and hair driers. You're not safe anywhere.
Even in the 80s and before, there's the world's nuclear arsenals; if the machines had no sense of self-preservation (which the film is inconsistent about, see Adaptation-Induced Plot Hole), then it's game over before you even start.
