A 20lb weight can kill a person from a far lower altitude than a parachute could meaningfully slow its descent. Parachutes aren’t magic.
Helicopters also have this "death zone" where an engine failure would not allow them to autorotate and have a controlled landing. And helicopters are a lot bigger and heavier.
Mosr cities don't have thousands of helicopters zipping by autonomously above our heads.
I wonder if an issue could be detected in most cases and the drone could immediately seek a safe landing, say on a building rooftop.