I think that unions are a great thing - when it's a collection of workers banding together for the betterment of their lives.
Unfortunately this usually isn't the case. Unions are run like businesses, with bosses on 6-figure salaries and a compete corporate structure. Like all business' they need to profit and in order to profit they need to show that they are 'working in their members best interests' and keep pushing for more. This generally pushes the industry too far and actually leads to them hurting their members, making them unemployable and ruining the industry
Whilst I do generally support trade unions in an idealised format, I agree it can go far too much the other way.
My union (NSW TF) gave up on large pay rises a while ago. The teaching profession is currently undergoing many changes so the union focuses on making sure the transitions are as smooth as possible, and as few as possible are left in the lurch.
Look at other developed countries with similar populations to us - Canada, Sth Africa, Austria.....do they have their unique brands and models? No. We just got very lucky. Very stiff tariffs helped too. 85%. It meant that most major brands at some point have assembled in Australia. But with the trend towards globalisation, and free trade, could it last? No. Ultimately our $30/hr workers were building a product that the market didn't really want anymore, and the $5/hr workers in Thailand were. When I bought a new car in 2013, it was a Thai built Fiesta, because there were no Australian made cars at that price point. I got rid of my mint condition VX because as my daily car it really was too big, thirsty, and uninvolving to drive.
You have to consider if the average family really needs a large, RWD sedan/wagon when for nearly half the price they can get a Corolla/Mazda3/Golf that will be fine for 95% of all trips.
Greedy unions are sadly one thing, but ultimately Holden signed off on the VE when oil was $20/barrel. By 2008 it was $140 plus! That's one of the things that killed it. Globalisation and an improved Asian auto industry mean there were cars coming out of Korea, Thailand etc that really were quite alright.
Also consider this - in the mid 90s, a new corolla was $22k drive away, and the Commodore was $31k. Now, the Corolla is still $22k, but the commodore is now closer to $40k.
So many reasons......