Australian edge errors

Picture 1) Australia  KM# 65  10 cents  1966-1984  Elizabeth II (2nd portrait)
https://en.numista.com/catalogue/pieces1282.html

 I have had this 1968 coin for a while, and was going to ask is the edge description of reeded/milled on the above page correct, as I had a coin with a smooth/plain edge. Then I got a second coin (1969), but that did have a reeded/milled edge, so guessed my smooth/plain edge one was a mistake.

Picture 2)  Australia  KM# 80  5 cents  1985-1998  Elizabeth II (3rd portrait)
https://en.numista.com/catalogue/pieces1567.html

 Then, the other day I got this coin (in the middle) and now wonder if it is a common error with Australian coins that quite a few do not get the edge reeded/milled when supposed to? Neither of the above pages mention this; the dates of my two (1968 and 1987) are 19 years apart; and they are different denominations. I wonder if anyone knows about these, and has any, or other denominations ?!  

                                 

Consider the possibility that the reeded edge may have been worn smooth through heavy use.  I've seen many American coins with reeded edges worn smooth after decades of wear.

I get these a lot, mainly older type but mainly 10 + years old, on  5, 10 and 20 cents. They are caused by usage and are worn. Never seen a new coin without milling. I go to Hong Kong once a year and see this wearing on the 1 and 5 dollar coin as well.
Glen.

ZacUKPicture 1) Australia  KM# 65  10 cents  1966-1984  Elizabeth II (2nd portrait)
N#1282

 I have had this 1968 coin for a while, and was going to ask is the edge description of reeded/milled on the above page correct, as I had a coin with a smooth/plain edge. Then I got a second coin (1969), but that did have a reeded/milled edge, so guessed my smooth/plain edge one was a mistake.

Picture 2)  Australia  KM# 80  5 cents  1985-1998  Elizabeth II (3rd portrait) 
N#1567

 Then, the other day I got this coin (in the middle) and now wonder if it is a common error with Australian coins that quite a few do not get the edge reeded/milled when supposed to? Neither of the above pages mention this; the dates of my two (1968 and 1987) are 19 years apart; and they are different denominations. I wonder if anyone knows about these, and has any, or other denominations ?!   

                               

I know this is kind of a cold case, but I have a 66 with a totally smooth/worn edge. Not even with a 60x loupe I can detect any trace of the reed. It's a bit strange that the rest of the coin isn't equally worn. But then again I have a 83 and even a 92 where the edge looks worn, but the reed can be seen with a loupe. So I guess Enlilninlil and Cerulean have a point.

Look at this from Poland, it might be something similar?

The flat rim is seen on french 1 franc coins that have been used for a long time in slot machines : each time they are used they fall on the rim where abrasion is huge compared to sides.

Regarding polish coins : it seems the reeded rim coins are a little widder that the flat rim coins. The difference may be juste half a mm but may be enough to explain what is observed. The coin in the middle shows half reeded rim : it shows it's coming from the way the coin is struck.

The coins' thicknesses are the same, it's just that somebody took the reeds away mechanically to make simulate a 1 DM, which was worth a lot more!