Only 2% of car crashes are caused by mechanical failure and nearly all of those are from improper maintenance rather than vehicle design flaws.
If you're thinking about the scariest plane crashes, where the plane hits the ground at more or less cruise speed, you're right. But, when a crash occurs during take-off or landing (and that's most of the crashes, although they don't tend to capture the public's imagination as much as the others), the chances are much better. There are some photos of pretty badly broken up and/or burned planes (e.g. https://www.nbcnews.com/news/world/emirates-jet-burns-runway...) where you would be surprised to hear that all or most passengers managed to get out...
This is not really attributable to planes having great safety features though, it's just the type of event which is most survivable (and which they therefore spend fewer resources trying to minimize).
It's basically like saying that people rarely die in car accidents that occur in parking lots. That's neither the reason for nor the result of the modern safety features.