I don't know about the US, but nowhere in Britain is it technically legal to park a vehicle on a public road. Legally it has been abandoned as soon as you get out of it and start to walk away. Not only can it be removed and destroyed, or sold if that is what the authorities choose to do, but you can be fined for depositing litter. This technical position is clearly absurd, and a workable arrangement has evolved, just not so far encompassed in law.
The same law (largely) applies here, and if you leave your golf cart by the side of the road while you're shopping or working you have technically abandoned it. The reality is of course quite different, and it is accepted in normal life that carts are so left. What is different "overnight"? Who is to say what constitutes "night" in this context? It certainly isn't just when it's dark, because it's dark from around 7pm and lots of golf carts are parked by the side of the road, their users shopping or eating. So when does "night" start? When you go to bed? I have neighbours who are up and active while I'm asleep, and vice versa.
The point I'm trying to make is that this "law" is completely contrary to normal practice, and at the end of the day law must be brought into line with common practice. It's how laws usually evolve - a gradual period of increasing "disobedience" that is ignored, followed eventually by a law being completely abandoned. Whether it's ever repealed is beside the point - there are many ancient and obsolete laws that are technically still valid in Britain, and by extension also here in Belize.