Never walk behind your bus!

Recently we were given these little cards about how to conduct walk around checks safely. In bold letters at the bottom of the card it says "NEVER WALK BEHIND YOUR BUS." I was pondering how we are supposed to check for leaks, if the tail pipe is secure, if the engine bonnet is secure etc. if we can't walk behind the bus? Also why do they consider it more dangerous to walk behind the bus than to walk in front of it. If the handbrake failed there is just as much chance of it rolling forward as there is it rolling backwards!
I did notice that on the day we were handed out these little laminated cards, that a large quantity of them ended up straight in the bin!!

More health and safety bullshit