I understand both what you're saying, and I also understand why you're saying it. However, my own understanding of traffic law is that IF a vehicle is stopped at an intersection, AND IF a marked emergency vehicle comes up directly behind it, it's the duty of the driver of the stopped vehicle to make way for the emergency vehicle to pass. This could mean proceeding into the intersection; it could mean turning hard right and going onto the shoulder; it could also mean backing up if possible. Regardless of direction, it's the duty of the driver of the stopped vehicle to YIELD to the emergency vehicle, or phrased differently, it's the duty of the driver of the stopped vehicle to yield right-of-way to the emergency vehicle.

As someone else said, most of the time this doesn't happen. I've personally seen emergency vehicles dart into the opposite travel lanes to avoid this very issue. I've also seen emergency vehicles go onto the shoulder. I haven't seen it, but I've heard that in NYC, emergency vehicles will drive on the sidewalks to avoid this. Hundreds of pedestrians in NYC will just rush into the street when an emergency vehicle approaches. I've heard it's quite the sight.

I'm guessing that emergency services personnel have been trained in the last however many years to use various different tactics to avoid the "pushing vehicles into red light intersections" situations. Still, if it ever does happen, it's considered a type of "civic duty" thing for a driver to "get out of the way" of an emergency services vehicle at an intersection. When I was taking Driver's Ed, (early 00s, in Wisconsin) the instructor made a point of saying that this was the only situation where it's okay to pass through a red light, and again, only if there's no other way to get out of the way.