I didn't quite understand the benefit of deliverbot, as compared to the same service with people. Is it just $x/hr cheaper to leave the person out of the driver's seat, so I'll rent y% more things than I do now? Or is it more about the promise of unusual delivery times that's going to change my behavior?

Certainly the cheapest way to do a vacuum rental business is to hand out the vacuums in-person at a warehouse. Some of your customers drive by your warehouse on their way to and from work, and maybe some of your farther customers would use an existing parcel delivery service. I'm not seeing how deliverybot can change the game, there, except maybe to shave off a little part of the rental cost.