Business can generally set their terms of sale, of which payment is one. Postpaid accounts are a risk to telcos and they will not generally offer one without payment details and authorities on file.
As for your experience with Telstra ‘service’ it is infamous for a reason.
I understand about giving payment details BUT they would only allow a transfer of account if it was direct debit hence the need for banking details. I have a AAA credit rating that was not even checked.
I’m sorry Phil but I don’t understand what you mean by “require cash amount”. How does this work
This has gotten well off topic for budget phones and photography so I’ll try to find a better topic. I also edited my reply above. I linked that earlier reply in this other relevant topic. A bit circular between here and there for sure 
phb Thanks for your suggestion. I phoned Aldi mobile and they said that the $99 sim card that allowed free phone calls was a promotion and not available any more.
It is a promotional item that is offered in-store 2 or 3 times per year. Once you have purchased one you can renew it online every anniversary. That aspect has been posted numerous times in multiple topics. If you are interested in one just watch the Aldi ads for when it offered again, and someone might also post it on this forum.
Just buy a SIM from them for $5 (you get $5 PAYG credit when you activate the new SIM) then get the $15 a month plan until they put the $99 package up again. It, the selling of the plan, occurs at least once a year. Or you could just get their Pay As You go (PAYG) recharges and use that until the plan comes up for sale again. Some stores still have the packs available, you just need to ask. Once on the plan you just renew it before it expires every year, no need to buy one from a Store again. If ringing Premium numbers (and they may not support many if any) you will need to keep topping up your Pay As You go funds though as these are the funds used that the monthly or Yearly plans do not support eg International Roaming uses PAYG. PAYG funds last 365 days unless you use them all up or you top them up which then extends the date by another 365 days
