I believe that they were responding to this specific part of your comment:
> But the idea that drones must keep track of which individual properties allow flight above and which don't, and try to navigate some around some kind of patchwork accordingly, is simply unpractical and unreasonable
Flying over public roads would be a way to avoid flying over properties that do not allow drones and would not be unpractical.
But why?
If you're concerned about safety, you'd prefer an out-of-control drone hits a car instead of a backyard or farmer's field?
And if you're concerned about noise, homes tend to be along roads anyways. So it's not going to change that.
And FYI, they're basically always below 500 feet, so they don't hit planes.
I believe that they were responding to this specific part of your comment:
> But the idea that drones must keep track of which individual properties allow flight above and which don't, and try to navigate some around some kind of patchwork accordingly, is simply unpractical and unreasonable
Flying over public roads would be a way to avoid flying over properties that do not allow drones and would not be unpractical.