I'm not sure why you think it would be okay to fly over non-highway streets, where presumably there will be pedestrians. Already there has been an injury caused

I'm not sure why you think it would be okay to fly over non-highway streets, where presumably there will be pedestrians. Already there has been an injury caused by a drone falling on top of someone (http://www.bbc.com/news/technology-26921504 http://www.bbc.com/news/technology-26921504). Regarding avoiding power lines: is that actually feasible? Either you have to program a GPS route from the warehouse to the delivery address avoiding all obstructions, or you have to use some kind of radar so that you can detect obstructions even in fog (or maybe just not operate in low visibiliity). It's not a trivial problem, and I'm not sure if the proponents have really thought it out. PS, if you're going to downvote my comment, at least explain why.