[panic]

What do you mean by "run more efficiently"?

Just focusing on space efficiency: very dense cities could build an underground transportation system connecting people's homes directly to space-efficient, centralized facilities. Instead of having a kitchen, you would order food or freshly-prepared ingredients to combine yourself. Instead of doing laundry by hand, you would send it to a centralized laundry facility, which would clean it for you and send it back. Trash would be disposed of using the same system. You could also use this system to store and retrieve things you use infrequently, so they don't have to take up space in your home.

A system like this would enable higher density by reducing the number of facilities you need in and adjacent to your home. It would free up road space by focusing commercial traffic on these centralized facilities instead of distributing it throughout the city. And it would free up road-side space by lowering the demand for laundromats, supermarkets, and so on.