Ways to make Drones Work when they are small for businesses

I think drones like Bezos from Amazon is talking about could work if:

They were only allowed to fly under 400 feet above the ground, and they had to fly above 10 feet above the ground so they would clear all human foot traffic on the ground and only dropped from that 10 feet or above when they made their deliveries on a porch or in front of steps to a house. Also, if they were going to be out an about they would have to have protective housings made of lightweight foam to protect people's eyes and body parts. In other words propellers could not be exposed at the tips to the air but covered inside of housings made of protective hard foam that is very light. They also would have to have avoidance mechanisms in place to avoid objects like power lines, trees, high trucks (both pickups, delivery trucks and semis etc.).

I could envision a UPS, Fedex or other truck driving to a suburban area and when the truck stopped for example, drones flying out the top of the roof to local deliveries. LIkely the driver would stay parked while 20 to 100 drones flew out of the van roof to deliver packages throughout that suburban area. Then they would fly back to the truck and the truck would go to another area and do the same thing there.

And I think regulations to require instantaneous grounding of all drones in the country should also be in place in case terrorists used them to deliver C-4 to one or more locations, for example. So, though drones could be very helpful making deliveries they also could deliver bombs or guns that could be shot while flying. So, regulations would necessarily have to be strict.