A UK switch Wall plate is (nominally) 8.5 cm x 8.5 cm = 72.25 cm²
An Australian (US) wall plate - for both Switch and (dual) Socket-Outlet - is 11.5 cm x 7.5 cm = 86.25 cm² A UK (dual) Socket-outlet is 8.8 cm x 14.5 = 123.25 cm² - almost 43% larger than the Australian dual Socket-outlet !!!
The "Mechanisms" can be switches, neon indicators, 8P8C LAN Connectors, TV Connectors, RCA Audio connectors, DIN Audio connectors etc. - and "blanking plates" have their uses in that, where a certain "connector" is not "commercially available" it can often be "made up' by inserting it in a "blanking plate".
Of course, the "Extra Low Voltage" devices may not be used on the same plate as "Low Voltage" devices.
However, using the same size "wall plate" for both Socket-Outlets and "Switch" (and other) "Mechanisms" makes it possible neatly to combine Socket-Outlets and "Mechanisms" in close proximity.
Note that any plug can be inserted in a socket-outlet of the same or higher rating, but not into a socket-outlet with a lower rating.
So, a 10 A plug fits in each of the five types of socket outlet, but a 32 A plug can only be used with a 32 A socket outlet.
While 15 A socket outlets are often used in domestic situations (cook-tops, ovens and air conditioners) - and in Caravan Parks - very few people in Australia/NZ would have seen a 20 A, 25 A or 32 A socket outlet. (This may change with the introduction of EVs.)
A 15 A plug cannot be inserted into a 10 A socket-outlet - and so on.
By the way, Schneider (Clipsal) "Australian NZ " style light switches are available on UK "Wall-Plates" - with up to 4 switches per wall-plate.
Made of high impact resistant polycarbonate components
You may note that "Australian/NZ" Light Switches are rated at 10 A.
This is because "Lighting Circuits" in Australia/NZ are rated at 10 A (not 6 A) - using 1 or 1.5 mm² conductors.
Hence it is quite permissible and often done to use a "standard" 10 A surface-mounted Sacket-Outlet (without any extra individual switch) to supply a light fixture in a roof-space.