I think those in VCE overestimate just how hard it is.
Looking back, it seems so much easier. Going to university and just generally giving your brain those extra years to develop is amazingly helpful. In addition to the fact that for most of the state, VCE is the first time they ever seriously studied or put effort into it. It's the first environment where they were expected to seriously learn and be meaningfully tested. All the other years you were more or less just expected to be present. Many here (not I) went to good schools or private schools where this isn't true but for the majority of the state, VCE is the very first time you do all of that. You develop study skills, organisational skills, etc all on the fly. Going back and doing it again would be far easier i feel.
I think most teachers have the potential to get 50 if they try. Keep in mind to teach it, you usually need a qualification in it. To teach math, you need a university level qualification in mathematics which goes *far, far* beyond VCE. Methods is trivial for people who hack it all the way through that. Similar for Chemistry. It holds true for a lot of subjects. Some are more difficult like "Biology" which combines like 5-10 different things you can become an expert in. Just by virtue of this most teachers would do rather well i think.