LIRR, sorry to break it to you, but before radios were prevelant, and even to today, conductors and yard foreman mark up cars, on the corners, so the switchmen know what tracks to send them to. We use chalk, or grease-pencils, to make small doodles. A far cry, from the retards with a case of Krylon, obliterating reporting marks, and all other info on the car.
Look at some B&W pics, from before WW-11, and see the huge amount of writing, done by railroaders, to make the switching easier. Getting bored while standing on the lead, some brakeman probably doodled a picture, and the craze was born. What we do, is harmless, and has been going on, since trains first needed classifying. Every day, while switching, we have to stop, and find a number on a car. Faded on the ends (or on a flat, not there at all) and painted over on the sides, sometimes, it's not able to be seen, so it's off to the rip-track. Huge difference between that, and the "Colossus of Roads" cowboy, with his pipe, and unique sayings underneath. Or the Wildman, the "Whistle", the "Appocolypse Productions" cracked egg, the LV flag, and on and on......