It's the urban sprawl. Urban planning in cities like Melbourne grew into a massive sprawl because they were factoring in the invention of the car. A lot of the layout of European cities were set before the car was a transport option. Everything was based around roughly everything you need being roughly within 30 minutes walking from your residence. The design was around little hubs of settlement. Which then could later be easily connected via train lines and other transport.
Cities in Australia, like many in America, spread out post-WWII with cars in mind. It's a completely different type of urban planning. The problem is, it was designed around you driving places, not walking. Things got further apart. The urban sprawl expanded. The mix of commercial and residential got more separated. You don't walk home from work and pop into a deli on the ground floor of a nearby building to buy some food for that night. It's designed around driving to a supermarket weekly. Stuff like that. It's a different way of living.
The European design lends itself better to building transportation networks, you're linking the little hub people living in. Put one train station in Every suburb in Melbourne, it's still a massive area, too inconvenient for most people to walk to. Do European cities have a problem with not enough carparks at their stations in the cities? Not really, no, many don't have car parks because people can just walk to them. You have situations where you have to decide which of the many station options are near you?
Catch the train through the country side of Germany. It's lots of little towns connected via trains. Little settlements, radiating from the cities. This is because the urban design was pre car.
Post War, European cities rebuilt on the old urban planning designs, versus those that went with new designs, similar to the US and Australia don't have these problems. While the new layouts do. It's actually a really interesting subject. Yes you could build the infrastructure, but it'll cost too much money. Our countries leaders are too dumb to spend the money on quality of life projects. Instead focusing on profit, squandering things like the mining boom which could have been used from such transformative public infrastructure and public good projects. While countries like Norway didn't squander there's and are now building insane infrastructure projects.