The Chicago with only one mode of passenger transport: the piggy-back ride.
Among other things, this has created a servant class of musclemen and a leisure class of Geishas. One might expect the city to have densified to keep down the mileage. It did not, for the musclemen are incredible beasts of burden and can easily carry the truly dainty Geishas from one end of the city to the other.
Gyms are a ubiquitous sight. Practically every neighborhood has at least one, from the local franchise of the mega corporate chains to the small family business operation and to the pop-up of roving journeymen. Most of these places also serve as central dispatchers, fielding service calls from riders and then doling out the requests to their members. A turf war periodically erupts and engulfs the whole city.
At first the Geishas and their musclemen piggy-backed on the streets. But after one too many scuffles with pedestrians, the city decided to fulfill the dreams of an earlier age and laid out an extensive network of elevated walkways. To help cushion the feet, they are landscaped with industrial strength turf.