Bigger aerial photography drones throw some a redundancy in - a hexacopter should (but won't necessarily) survive any one motor/prop/ESC failing, and an octocopter will most likely survive one or two. A second or third GPS receiver isn't super uncommon, and there's a decent pile of parts that can fail gracefully (return to home if radio signal is lost, for example).

You're still absolutely right though - there are plenty of parts that will turn a multicopter into a brick if they fail, including stuff like manufacturing defects that are undetectable in advance and entirely outside the pilot's control. In some places, it's mandatory to have something like a ballistic parachute to fly over people, and there's a good reason for that.