This isn't a constant linear crash rate. Each crash creates the impetus for a more robust product generation. But in the beginning, you should expect to see things go wrong. See SpaceX for example.
People getting hit on the head is not acceptable whilst the technology and standards mature. A few rockets blowing up, without hurting anyone, is acceptable whilst technology matures.
So far as I can tell - nobody has (yet?) been hit on the head with a delivery drone.