There is a delightful little town on an island off SoCal coast, Avalon, where the main mode of motorized transportation is indeed the golf cart. The shaping constraint is geography, the town is on an island by a bay surrounded by steep hills, medium/long distance travel is out of the question. Would be difficult to transition nearby LA megalopolis to such a mode of transportation without enforcing political barriers to travel, which in practice would require a ruthless tyranny.
https://en.wikipedia.org/wiki/Avalon,_California#Transportat...
"The main method of transportation within the city is by small gasoline or electric powered motorcars referred to locally as "autoettes". These include numerous golf carts and similarly sized vehicles. Vehicles under 55 inches (140 cm) wide, 120 inches (300 cm) long, and less than 1,800 pounds (820 kg) may qualify as an autoette. Any resident may acquire an autoette permit with the restriction of one permit per household. It is very difficult for a private citizen to get a permit to have a full-size vehicle in Avalon."