What Is the Difference Between SVO and OVS?

There is a very strong statistical tendency for languages that have no case marking or roll marking particles to be SVO. That makes a whole lot of sense to me because it makes it much easier to tell which word is which. But why SVO and not some other random word order? We've actually been thinking about doing a whole episode talking about ambiguity. All languages have ambiguity somewhere and it doesn't harm communication that much.