Even worse than that worse case is it's a unfused box with a component connected directly across the mains, therefore a fire hazard waiting to burn your house down. Much like the cheap USB chargers out there.
Nozzle
In one way you are "correct", in that BS1363 requires that Plugs inserted into such socket-outlets include a (maximum) 13 A fuse to protect "what"?
Possibly the external flexible wiring to the device concerned.
However, in this case there is no external wiring.
If the BS1363 socket-outlet were to be on a "radial" limited to 20 A, any current exceeding 20 A would "trip the breaker".
If the BS1363 socket-outlet were to be on a "ring" limited to 32 A, any current exceeding 32 A would "trip the breaker".
In both cases, while the socket-outlet may suffer damage due to "overload", and (possibly) poor design, the "house wiring" is protected, by the MCB or whatever.
While I have no interest in "plugging in" that which may contain a voltage "underrated" capacitor (which may develop a "short-circuit), what would happen would be that the device concerned would be destroyed by the excess current concerned and the MCB (or RCBO) would "trip" very quickly, protecting the Household wiring - which is that which it is designed to do.
In Europe there are 16 A outlets without "fuses" in the plugs, so a device which fails with a short-circuit would just "blow the breaker".
Then there is this
https://commons.wikimedia.org/wiki/...cket_styles_for_different_current_ratings.jpg
which may horrify you!
You may note that a (basic) 10 A device
could be plugged into socket-outlets of up to 32 A capacity - without any other "protection" at the plug.
(Not that over 95% of Australians are likely to have ever seen a socket-outlet of over 15 A capacity!)
If you look at the photos, you may discern that all of those socket-outlets are (virtually) the same - apart from the shape for the earth pin, preventing any 32 A plug being inserted into any lower rated socket-outlet - etc.
Of course, why some of those socket-outlets are rated "lower" is because they are required to be installed on circuits for which the wiring (and its protection) is rated lower.
From this you may realise that a properly designed socket-outlet for 10 A could easily carry 32 A, if it was allowed to do so.
The reason for which it is prevented from so doing is because of the current carrying capacity (or lack of it) of the conductors in the building, limited by the required MCB/RCBO.