While I agree you want your own vacuum for small spills, it would not be up to the fancy one. If the fancy one can be there in 3 minutes, do you even need the small one? 3 minutes, with a 20mph deliverbot just means one unit on call for ever 2-3 square miles (this is the bare minimum, of course, you need more, but it shows what you could get away with.)

It saves a lot more than $x/hour to leave a person out of the driver's seat. To have a driver, you need a truck able to handle a human and the cargo, not the tiny pod for just the cargo. And the driver has to sit there waiting. And if you have 5 requests you need 5 drivers ready at the depot. And you need big depots. A deliverbot depot is a small warehouse where the bot can quickly go down an aisle, grab the desired rental item and scoot out the door. It's a garage somewhere. (After robocars, I expect there will be some garages for rent.)

Handing out in person is actually not necessarily cheaper if it needs a person and a warehouse where people can go and park. And it's vastly more inconvenient for the person. I'm talking about a system where you are at home, and say, "I need an X" and within 3-5 minutes an X is sitting in the garage. To me, if the time is short, it's almost as good as having the thing in my garage all the time. (The deliverbot can be given a code to open the garage door.)

Except in some ways it's better. It doesn't take up space in my garage, it's a much higher quality unit than I would have bought, and it cost me less than buying.

Now a vacuum may not be the perfect example, since you might have to clean it every time which you don't do at home. (Of course, bump up the robotics and then it is cleaned out by other robots, or is a robot itself, like the Roomba's grandson.)

It doesn't matter what it is, as long as it's portable, and a quality unit is expensive. It might be a fancy kitchen appliance or a machine tool. It might be a high-resolution projector for a presentation. It might be a backup disk you want to store offsite or a specialized tool. If it can come by deliverbot for a low price, it could make sense.