I posted about this series of documents, B6525 in the National Archives of Australia back in 2014. At the time, only some of the forms had been digitised. Having another look at them today, I find the whole series digitised, as well as another series, B6526, which are the name index cards for Series B6525. The cards are sorted alphabetically in four sections, according to whatever reason was, or was not given. Not too hard to match up with the folders in B6525.
Use the Advanced Search option and pop either number in the Series box. In the results form, click on the number of records - ie, in B6525 you will see 29. Click on that to get the full list. B6526 shows 4 items.
James Boyne of 34 Eltham St, Flemington did not get away with a two line reason for not enlisting. The Committee required a more detailed explanation. His letter follows his form.
Seeing that enlistment was still voluntary, these men could not be forced to enlist, but it all added to the pressure.
So if you are wondering why some people didn't enlist, the answer could be here.