Like, why would you ever build a city differently in the first place?

Exactly. Unfortunately, in Australia, we tend to borrow stupid ideas from the US to make money and have sprawling suburbs with zero amenity.

For instance, we had a new suburbian development within 20km from the CBD with the promise of schools, community centres etc. in the early 2000s. When all the houses were bought and built, suddenly there's no money for amenities so they just sold the land to developers who then put more houses in. Now the only way to get anything you need is by car because there's no train or buses because it was supposed to be accessible by bike/walking but now isn't. And not to mention gridlock of vehicles looking to get out of the suburbs for food etc. out of the one intersection provided.

I would love 15min cities without cars for my country but the attitude to cars here is similar to the attitude about guns in the US.