The pops/motors are counter rotate in pairs, one CW the other CCW, with 4 props/motors if one goes out the other with the matching rotation cannot generate enough torque to compensate and the aircraft starts to spin and quickly will crash. Aircraft with 6, 8, or more props/motors can sustain a loss of one or more can can still fly and land safely and in control.

These commercial aircraft are equipped with parachutes and safety systems to bring them down safely in the event of a malfunction. Additionally, each aircraft has a maintenance schedule just like a manned aircraft to ensure a very low failure rate.

I have seen a quad throw a prop while in the air and come down hard, not a pretty sight, they break more than they bounce even if they hit the grass.

The ultimate goal is near full automation of delivery aircraft. Crawl, walk, run...

How long will it take for a crook to dial in a drone frequency to steal its merchandiser especially when Best Buy start doing things like this...

Flight controls and all communications are encrypted to prevent just such a happening. There's a lot of smart people working these projects.

Wait till the druggies realize Oxycotin is being transported within a shotguns blast distance...:duck: