Given what they have done with drones, it is funny seeing the comments here.
A plane that can fly 4 people from rooftop to rooftop in a city, without paying a pilot, avoiding street traffic.
Given a typical flight might be 10 miles at most, range should not be an issue.
Real question is whether you can create the infrastructure for rooftop pickup/dropoff.
You're comparing what in effect is little more than flying a kite to commercial passenger service. If a drone crashes you just go to Radio Shack and buy another. But both in terms of regulation and operation, it's (more than) a bit more complicated than that when there might be dead bodies in the wreckage.