Why are Australia’s most populous cities located along Australia's coasts?

The coastal areas of Australia are most accessible for trade and travel, have the best climate and leisure activities, and there is enough water available to meet the needs of a large population. hope this helped

Cultural convergence is the theory that two cultures will be more and more like each other a very notable example of this is around the u.s.-mexico border, where 

Idon't know. the question you are trying to ask doesn't make sense.