There were plenty of proposals back in 2021 about having highways in the sky for drone delivery operations, at least in Canada, so such incidents are avoided, as relying on technology alone isn't enough and the risk plans are only to mitigate rather than eliminate the risks.
That being said, drone delivery will not really become a thing unless the endurance issue is resolved, like a new breakthrough battery technology that gives you at least 4 hours flight time (hybrid drones are noisy), as for any drone to have a proper impact, it should have three items checked: endurance, payload, and range. The last two are pretty much resolved by having modular payloads and flying over the internet, the first one is still pending.
I'm not sure they need endurance, if they're cheap enough companies can just buy a fleet n times larger than the number they need in the air at any given moment and have the others charging at base. Or more likely buy some extra batteries and have someone employed to swap them out when they're getting low.
Why do you think there is any problem with battery endurance? I’m quite sure Amazon has run the numbers on battery life for individual flights and for the lifetime of battery packs many many times. It’s just economics. And has basically nothing to do with safety. Unless a battery fails suddenly and spectacularly, which is rare and probably isn’t what caused it to crash into a crane.
It is for both, manned and unmanned, providing also a map of the network coverage in these “highways” and other active drones as well. I remember seeing a proof of concept platform that provided such functionality in Singapore, I am not sure if it became a reality later though.
It's not a limit, just from my personal exposure in the overall drone delivery, 3-4hrs would provide enough time with margin for any safe delivery, beyond that is definitely better but probably is too hard to achieve. Keep in mind the actual flight time will be less than that, accounting for payload weight and environment like wind and temperature. In cold weather like Canada, the batteries will consume some of their energy to heat themselves before taking off.
What's the math that gets to 3-4 hours? Do the drones usually multiple deliveries in a flight? In my metro I would have assumes that any place is less than 30 minutes flight time from a Whole Foods or Walmart for example. How long does the actual safe delivery take? I assume it just lowers the goods and doesn't wait for the customer, right?
Edit: The Internet tells me that delivery drones fly at 40-60mp/h which is much faster than I assumed and makes the 3-4 hour window even more surprising to me.
That being said, drone delivery will not really become a thing unless the endurance issue is resolved, like a new breakthrough battery technology that gives you at least 4 hours flight time (hybrid drones are noisy), as for any drone to have a proper impact, it should have three items checked: endurance, payload, and range. The last two are pretty much resolved by having modular payloads and flying over the internet, the first one is still pending.