Let's be honest, Pat Cummins was actually scared. And that was the best thing that happened to him. Australia was being criticized a lot and a lot of people also said that Australia was not going to make it to the semifinals. Even I was thinking the same thing when Australia was in really bad situation against Afghanistan. I thought India was going to take the trophy without any big trouble. But Australia turned things around. Australia where scared and that is exactly what enabled them to perform better and make themselves. Push harder for better performance.
And let's be honest India didn't have any true competition throughout the whole tournament. So I actually think probably India took things a little easy.
I agree with your opinion about the Australian, but you are missing few things they are the best learners and having best cricketing minds as well which give them edge in cricket and just because of this currently they are ruling the cricketing world without spending huge funds like India.
After first two matches I was also not sure about their chances but as they fight back and done things in next 9 games it's surely giving all how they can change the tables with their own match against Afghanistan and then having semifinal against South Africa were the best of them before this big show against India in final where nearly 90% Indians were sure for the win and many ads and other social media related material was also ready but suddenly Aussies done magic and bring them down.
Ricky Ponting give them good tips which works, and they were able to bring down one of the best Indian side in ODI history with bang and won this world cup in front of 100K fans at Narendra Modi Stadium, Ahmedabad.