That all sounds great, except that helicopter often operate at less than 500 feet above the ground. What happens when EMS is flying at 300ft and crashes into their delivery drone? What about law enforcement? Powerline and pipeline patrol?
I think the 'managed by exception' approach mentioned covers that. Given the gps and communications capabilities of the 'well equipped' drones they could automatically be ordered out of the area and/or excluded from the area. As they would would presumable be excluded from airports, infrastructure like powelines, etc.
In the North East, they even harvest Christmas Trees off the side of the mountain using helicopters, and that is well under 500ft.
The 'communications with other drones' mentioned suggests automated avoidance. Perhaps these 'well equipped' drones would listen for standard aircraft transponders, they seem to include such transponders since they are notifying air traffic control of their position. Avoiding low flying aircraft may be part of their normal avoidance.
I'm not saying they have it all figured out, just that they seem to be considering the sort of things you mention.