I've been a customer with ANZ for quite a few years now my promise was to move away from them to the first bank to offer Apple Pay but funny enough that happened to be them.
Now that Macquarie and ING Direct both offering Apple Pay. I've signed up for accounts for both of them as well. So I'm trialling three banks at the moment to see which one best suits.
Unfortunately when not quite there yet.
Definitely easier with the receipt but if it's a large transaction these days showing the transaction on a bank statement or on a mobile phone app should be more than sufficient.
However my experience has been It's easier to sort out if you've got them when transactions go wrong like you get double charged. Had this happened a couple times last year and thank god I kept the receipts.
This is normally what I do, A printed copy goes in original packaging as I normally keep packaging for large purchases for about 12 to 24 months.
I also scanned a copy with my phone for my records, which I normally keep on the computer. However I will also be attaching them in my Internet banking with Macquarie as they allow you to attach a receipt to a transaction from with in their Internet banking + banking app.