Well there is also a lot of oil used in transportation and...

Well there is also a lot of oil used in transportation and infrastructure to get fuel into petrol station to fill up a car. It would need to be transported from being drilled to being processed and refined, shipped and eventually put into a car. Most of these things aren’t centralised, think about how many petrol stations there are.

Electricity generation, even if using fossil fuels are fairly centralised, so coal gets transported to fewer places and split up less times to get to the power station.
Then electricity is transported fairly efficiently through the powerlines.

Even if people are using 100% coal power generated electricity, there is efficiency in drawing energy from the grid rather than from a resource that needs to be shipped.

Also a lot of EV owners in aust have rooftop solar, and that most of them charge their EVs at home.

Nuclear definitely will make EVs more environmentally friendly overall. But so far the people who can afford EVs have been selective about how they have been charging them.