It could be in large red flashing neon and people will still ignore instructions like this.
Even if the trash dumpster is a mere 50 feet away.

People just don’t care. Once it’s out of their hands, no matter where it ends up, it’s someone else’s problem.

One complex where I used to live, our trash dumpster was a full on compactor, very nicely concealed behind a small hill. Signs leading up would say, “No cardboard!” Signs plastered all over the machine, “No cardboard!” Yet, at least once, if not twice a week, the thing would be clogged because people would toss in boxes by the truckload. Not even broken down.
Meanwhile, just around the corner, a specific dumpster meant for cardboard only that would take all of 10 more seconds to get to.