I think zero-zero ejection seats are a good point of comparison here. These are the state-of-the-art ejection seats used by US fighters and bombers, designed to

I think zero-zero ejection seats are a good point of comparison here. These are the state-of-the-art ejection seats used by US fighters and bombers, designed to function from a dead stop on a runway. That's what you'd need for this to be useful in the flight regime most accidents occur in. Unfortunately, ejection seats suck to use. Like, mild chance of killing you, very high chance of breaking bones, almost certain to make you a few inches shorter from compressing your spine levels of suck. This is assuming that you don't hit anything on the way out, of course - and don't land in the fireball. And that's with trained, fit pilots who are expecting the ejection. Can you imagine what happens to Grandma who's started to lose bone density? Or the baby on their mother's lap? And that's before you start considering the issues with having that many parachutes and rockets in close proximity, or the weight. So that's why planes don't have features to save these people.