NO reason why people can't do training on a tourist visa. I'm sure plenty of visitors do diving courses, skydiving etc.
I have trained heaps of PPLs on tourist visas. The main thing is they can't WORK on this visa.
You could apply for subclass 402 but then may only be able to stay for the duration of the training.
I'm a visa sponsor for Subclass 420 so know my way around the system quite well. What they always want proof of for these is a "net employment benefit" for Australians. Doing a course here would certainly provide that.