Is the law of an open container right?

Considering the fact of a national from the Bahamas open container law is not real, Bahamians are aloud to walk with a bottle in the hand, but in the US the law is that you can walk with a open container with does not make no sense to me. The law should be taken away not being able to drink on the beach is simply and there is no harm people leaving bars are going to be drunk anyway why having a can in there hand make a big difference. Trying understand this law really makes no sense to me.