As someone who has spent a long time in New Zealand it was striking to me how many places you needed cash for in Australia. EFTPOS is not ubiquitous there like it is here.
I would hazard a guess you could make 99.5% of transactions with EFTPOS in NZ - the exceptions might be a few vendors at farmers markets (most take EFTPOS), sausage sizzles/ad-hoc fundraisers, fruit honesty boxes on the side of the road, etc. Maybe only 85% would take credit/debit, though.
From my experience in sydney/melbourne more places take credit/debit than NZ but also more places are cash only. Not as much penetration for EFTPOS.
I was in Canberra for a week late last year and I never used cash, everywhere took debit cards. Some had a surcharge for using debit over eftpos but I didn't see any shops or restaurants that were cash only. Market stalls were, unlike in NZ where mobile EFTPOS is almost everywhere.
It depends on when you were in Australia. EFTPOS fees for small amounts were essentially outlawed a year or so ago. That has made a big difference to pushing the final hold-out businesses into cashless in the last few months.
New Zealand for whatever reason I used cash a lot too. Australia you can pay stuff for small sums like $1 on card almost everywhere so no point to carry cash most of the time
NZ's government thinks (or thought, it's changed recently) that the market would sort it out so the current rates are up to 3% for credit and 1.5% for debit, again Mastercard's list is here: https://www.mastercard.co.nz/en-nz/about-mastercard/what-we-...
EFTPOS transaction are generally fee-free for all parties.
As someone who has spent a long time in New Zealand it was striking to me how many places you needed cash for in Australia. EFTPOS is not ubiquitous there like it is here.