What happened in Australia when they went for different fees for different subjects?

Last week, we featured six questions that need to be addressed by those joining the chorus calling for lower tuition fees for STEM (science, technology, engineering and maths) students in England.
Differential fees by discipline would be novel for the UK, but (as we explained in a 2014 pamphlet) they have existed for a long time in Australia, which has three different fee caps. More...