Rusty--I suspect that you are being a bit pedantic here. Whoever said that skiing is, or could be, a zero-risk, zero-injury activity? There are, of course, always risks, and the safest possible lesson ever cannot completely eliminate them all. I cannot imagine that anyone would ever equate "safety" with "zero risk." Risks are a given in skiing, as they are in most things, and injuries are not, in and of themselves, evidence that a lesson was not conducted with utmost safety in mind--given the risks. To me, "safety" implies that the instructor never exposes anyone to an unnecessary level of risk, and that an excellent instructor can reduce the risks that are given in virtually any situation--any condition, any terrain, any exercise, any trail, any movement. If there is an equally effective and equally satisfying, but less risky, alternative to a high-risk activity or exercise, for example, the instructor's job is to go there, or at least, to advise it.
Are there safer tactics? Movement patterns that put us at less risk? A better route with less traffic? Times of day that offer better visibility on this run? A safer way to do that exercise? Perhaps all you need is a reminder to wear sunscreen, that the light is flatter now than on the last run, that there is an exposed rock just below that little knoll, that you need a spotter before attempting that jump, that we should move and stop in a safer spot, that fatigue may be becoming a factor in ourselves and others, so perhaps we should back it down a notch for this last run, that your boot setup puts a lot of stress on your knees, that you might want to remove your pole straps before we ski these trees, and keep your partner always in sight, that we should ski this chute one skier at a time, that there is a dangerous intersection around the next bend, .... The list could go on forever. These are the kinds of things a safety-conscious instructor will do as a matter of course. They all improve safety. They all decrease risk. None of them guarantees that injuries and accidents will never happen, and when one does, it does not mean that the lesson was not conducted safely, or that the injured skier was not still safer--all things considered--in the lesson than not. None of these involves "compromise" of any sort.
You want to do something inherently dangerous? An instructor's job is to help you do it as safely as possible, to eliminate unnecessary risks. You cannot possibly ask for more, without simply not doing the activity. That would be a compromise, and it is rarely necessary. Yes, there are times when we need to educate students about risks they may be unaware of, and perhaps to encourage a different course of action. Almost never does "safety" require that we flat-out refuse to allow a student to pursue his or her goals.
Indeed, trying to avoid injury can, itself, be dangerous! "Trying not to fall," skiing defensively, and so on can actually increase risk.
I maintain that all these thoughts are inherent in the "Safety X Fun X Learning" side of the lesson equation. If the instructor sucks the lifeblood out of the lesson, compromising fun or learning in the interest of "100% safety" (ie. no possibility of an injury--an impossible goal in itself), it is a failure. But constant vigilance, awareness, and understanding of risks--without compromise--must take place. It is a three-poled polarity--all three points must be fully embraced. Where is the compromise there?