there's probably just missing frames

Similar to a car crash, you are generally safer in your padded engineered metal box than being thrown out of it, or thrown around inside it.

It’s like the difference between dropping a carton of eggs vs a bunch of loose eggs in a box.

An explosive release canopy for an ejection seat system on an airliner would just release the entire top half of the plane, and don't forget that fighter pilots are both wearing flightsuits and get specific training for the event.

Even beyond the material and engineering costs it's a difficult ask, probably better to just focus on reliability in the first place.

I remember seeing an article back in the 90s or maybe even 80s that was exploring the possibility of the entire passenger compartment separating from the wings and rest of the fuselage and parachuting down in the event of a major failure. The thing is, it would be ridiculously expensive to implement, and there are very few situations where such a system would be any better than keeping the plane in one piece.