Although I'm no longer in operations. Here's what I think, 95% of drivers do the right thing the vast majority of the time. There's a small percent that don't and cause the accidents and injuries. I think the msg was mainly for them.
However, Even for the 95%, the minority of the time, people will make a decision to save them a bit of time, but add potential for more accidents. Such as barnyard indicated in his quote. He made a loop around block instead of backing and this will cost 5 minutes a day (or less). That's what the main portion of the msg was for. To stop those backs that don't save us much time and can be avoided.