It is easy to say you can get so much tax revenue from this and that. It can be very sensational to make dramatic claims for so many billions of revenue could be raised and to grab the media headlines.
Why do the authors are so obsessed with increasing taxes or imposing new taxes? Why don't the author study whether all the governments' spending are appropriate or not in the first place.
There are enough taxes in Australia and we don't need more of them.
I think the authors need to take a cold shower to be intellectually sane. There is enough of this and no need for them to lecture people on this tax and that tax.