I don't disagree with you, but as someone who walks into a _lot_ of emergency scenes, it's really rare for there to be a hazard to worry about. Is it a thing you should consider? Sure. In reality it doesn't come up often enough to warrant "top billing" in a high level overview of how to do chest compressions.
In any emergency scene, the first thing to do is check for traffic to prevent the victim or yourself from getting run over (sometimes merely because you need to cross the street: while running to provide help in an emergency situation, you're likely to forget looking both ways).
If any one of those emergency scenes was outdoors and you didn't think of this, you're doing it wrong. And even if you've always remembered to do this yourself, it's essential that you explain it to others so they will remember it as the first thing to do.
