Your buyer is in the same state as you, and eBay are basing their estimate on that, using the regular (non priority) postage timeframe. Buy today, post tomorrow (Tuesday), delivered Thursday. 

Australia Post's estimate on their website is a general indication - 2-6 days covers all regular letters Australia-wide. Like, if they had a sign on their window to advertise it, it would say "Send a letter anywhere in Australia and it will be delivered in 2-6 days (2 days for local areas, up to 6 days for interstate locations)". Same goes for the priority estimates - 1 day is for within the same state (usually metro areas), 4 days is for interstate destinations. If you go back to your listing and put Perth's postcode in to get an estimate, it will show a longer transit time and later ETA. 

If an item is sent free postage, the buyer can't leave a star rating for postage as it's an automatic 5 star rating. They are still presented with the yes/no question if the item was sent untracked (and sometimes when it is sent tracked).

oh yeah. i forgot that has been added.

i ment to also say i allways use the tracking option on my items. not sure what the OP was posting but i would advise getting the tracking number and logging it into ebay on anything these days.

Rather than increasing delivery times, phone ebay with EVERY SINGLE PROBLEM AND TELL THEM HOW their ridiculous crystal balL is working. I received an item yesterday and the little tick box turned up . Did it arrive by the 21st.  I lied, I said YES.,  I KNOW IT GIVES THE SELLER A STRIKE, most don't. think it a harmless survey- EBAY MUST PUT A WARNING ON THIS -DO YOU WANT TO GIVE THE SELLER A STRIKE?? YES OR NO. Repeat, phone them for every one, and as a side benefit you may well become fluent in Filipino English.

If you answered YES it wont give the seller a strike.

That is why I said YES.  NO would give the seller a strike.

---

@davidc4430 wrote:

oh yeah. i forgot that has been added.

i ment to also say i allways use the tracking option on my items. not sure what the OP was posting but i would advise getting the tracking number and logging it into ebay on anything these days.

---

Only if scanned lodgement within handling time, otherwise you get carrier dobbed.

---

@asccoz wrote:

That is why I said YES.  NO would give the seller a strike.

---

This is an example of why it is dumb. It is supposed to be moving away from perception based rating to evidence based rating, Yet it is still up to buyers whether they want to say yes or no. Which may not be based on truth, or even accurate recollection. Having lodgement scanning is "lack of evidence" based.