This type of outlet is known as an "architrave" fitting. That is, it's intended for mounting in a door/window frame or skirting board without a box. Even the standard size fittings are often mounted without boxes. Generally, boxes are only used in with brick or concrete walls. Hollow walls like Gyprock or Masonite use either a thin steel bracket with tapped screw holes, nailed to a stud behind the wall, or for retrofits what's known as a "plaster bracket" which is a similar thing but hangs on to the edges of the rectangular hole with two clips.
That just seems so different to the way things are done in the USA. That there is no box to attach via a connector the house wire cable to (strain relief, so no strain on the actual wire connections on the back of the outlet). And that here, the box also helps contain any flying sparks from a failing connection, so the embers don't find flammable building materials to set fire to.
