In the US you spent a year choosing your candidates, but behind closed doors one of those parties spent all their time trying to push one candidate whilst the other party spent all their time trying to stop another.
The Australian system seems a little more honest, even though the roles of PM and President are quite different. We can elect a PM and the party can then choose to throw them out the week after. This happens frequently.
Regardless of the pros and cons of the US system, it does seem weird that Mr Head Honcho can end up not being politically aligned with the legislature. So much potential for stalemate, as evidenced by the past six years.