Spray paint cans came became widely available in the late 1950's I believe. I repainted my motorcycle in 1965using them. I reckon they were too expensive for the graffiti 'artists' to be using at that time. How things have changed.A different time to be sure. Before the invention of spray paint.
I was stopped at a train crossing recently, and to pass the time I counted how many cars showed no graffiti. It was about one out of ten. And that was just one side of the car, of course.