I don't know what the Tesla semi will cost in Australia, but normally we can more or less double the US price for most things (at least that is my experience). On that basis, the Tesla might cost around AU$500,000 which is roughly in line with many prime movers over here (according to my friend who has just bought another one).
It seems to me that for long distances, bulk movement of goods or people is always going to be a far more efficient mechanism than a scatter-gun approach of thousands of small carriers. Unfortunately the problem with such a system is that it needs to be created, at great expense, with an overall plan that not only includes the long-distance portion but also the "local" distribution or collection at each end. We have never managed to achieve this - even now we create systems of public transport that can shunt large volumes of people to and from a city centre, but then simply dump them a station with no way to get from the station to their homes, hence stations with huge car-parks!
We are now faced with the need to move away from fossil fuel, which gives us the opportunity to "start again" (especially for long haul transport). Sadly I have no doubt that you are correct, and that we will get it wrong once again. Moving to an age of AI and automation, with the chance to create a system where shipping containers (or equivalent) of various sizes can be loaded at source and then automatically placed on a train to arrive hundreds or thousands of kilometres across the country in minimal time and with minimal human "work", we will choose to continue using trucks because that's what we've always done.
The reality is that the government (civil service) is totally incapable of carrying out such a process and would likely spend decades and billions just trying to figure out what colour the trains should be.....