An autonomous drone has to be able to cope with cables, pylons, trees, plastic bags & other blowing detritus, flag poles & flags, wind turbines, terrain, buildings, birds, light aircraft, drones, wind, gusts, down/up drafts, frost, heat, cold, strong sunlight, reflections, snow, rain, hail, lightning, etc. It has to be able to do this day or night. Drones also have their own failure modes on top of all this.
If a drone can't avoid obstacles and fail to safe then it has no business whatsoever flying near populated errors. Not to mention that even if did operate safely then it's still a noise nuisance. It would be very sad indeed if people start taking potshots at these things or griefing them.