That's all well and good, but if you're to the point where you are going to use the Jaws of Life, the sticker on the window might not be legible any longer. There's also the problem that the electric motor may not shut off in a crash, and you can't hear it like an internal combustion engine. As a first responder, if you try getting someone out of the vehicle that's still running and you don't know it, you might be in for a world of hurt. First rule is your own safety, then your partner, then the patient. You don't want to injure more people. If that means waiting before entering a situation, you wait. If I'm in the accident, I'd rather not give the responders any reason to wait.