And because of the various printers involved in their self-adhesive stamps.
The Hibernian 2014 catalogue does list them like this:

For the Heritage stamps the Australian production is referred to as with "sharp points" , but why not for the other Australians?

The Irish Security Printers did use a "kiss die cut" with 13 teeth between the "tips'" OR 12 teeth along the long side of the stamp!

