There is nothing inherently convenient about cars, or about any
vehicle. It is the system that makes them convenient, and that system
includes both the vehicle and the infrastructure. Provide unlimited,
subsidized “free” car infrastructure, and cars will be convenient. Run
buses often, everywhere, all the time, and buses will be convenient.
Put everything in a giant skyscraper with computer-controlled
elevators, and elevators will be convenient. Trains, walking, bayou
boats, swinging from vines, conveyor belts, scuba diving: whatever it
is, if you throw enough money at the infrastructure you can make it
UPDATE: I should add that while I am quoting this approvingly, I do have issues with the word convenient, which I explained here.