And how much would all of those lead-acid batteries weigh?
The Lunar Rovers were much more than simple electric golf carts. They had 4 wheel drive using individual hub motors. They folded to fit into a very tight storage bay and had extremely tight weight requirements. They had navigation systems to help the astronauts find their way back to the LM. They also had a communications system capable of reaching all the way back to Earth. Sure, they were expensive because of their unique requirements. Show me a golf cart that could've met those requirements and we'll talk.