I'm sure your existing homeowner's insurance policy will cover that. I'm certain of it. It may add an extra $0.50 a year to your premium, because the odds are so small that:
(a) Your house will get hit by a drone
(b) The collision will cause damage to the building
(c) The drone will have no ownership identifiers on it.
(Hint: Not Amazon, which is what we're discussing here)
You don't currently purchase "uninsured baseball thrower" insurance, do you? Those things cost tens of millions of dollars of damage in broken windows every year, but we've figured it out.
My house has already been hit by a drone, albeit a small $500 drone, though there was no damage. And the owner asked if he could retrieve it so I lent him my ladder.
But as drones become more ubiquitous and the big ones become cheaper and more useful, then the chance of damage increases.
Amazon isn't just talking about legitimizing their drones, but legitimizing drones in general with an "anything goes" airspace below 200 ft.
I wouldn't make a homeowners insurance claim for a baseball through the window since claims mean higher rates and multiple claims can lead to blacklisting among multiple companies. But a 20 or 30 lb drone dropping 500 ft to my roof may cause thousands of dollars of damage, and unless I can identify the drone's owner (or even if I do and he has no money), then either I or my insurance company is on the hook for repairs.
Regarding the baseball. Usually, if the miscreant that threw it then ran away can't be identified, you just eat the cost of the window. That happens rarely enough that I'm still in favor of kids playing ball in the neighborhood.
If heavy drones are crashing down often enough to cause problems (let's say more than a couple dozen times a year in the US), then rules will need to be put in place to curb that, sure.
I think you and I are arguing from different scopes here. My whole premise has been regarding Amazon-owned (or other commercially-owned) drones operating in our skies. You're--rightly--concerned about that guy down the street picking up a 30 lb. machine for fun, and not being responsible with it once it causes damage or injury. I think we can agree in that regulations on the craft and on the operator would apply before it's allowed to fly. Maybe the operator should be bonded and insured, and should have passed some sort of certification. The aircraft itself should meet some minimum standards of safety and redundancy. OR, if the aircraft meets some higher standard of safety and redundancy, then any civilian can operate it because it self-enforces flight safety rules.
Those same rules should also apply to any commercially-operated drones of course, but I've been assuming that, e.g. Amazon, would do this out of self-interest. They don't want to deploy a fleet of drones only to have a massive PR nightmare when things go south.
And after all these rules are in place, in the instances where someone does violate the law and flies illegally, existing insurance and law enforcement schemes would be able to handle it.
All I'm afraid of is cutting off innovation before it can occur, due to an over-abundance of caution. That's all.
