The socket in your example is Type F, Schuko. Those are only available in recessed form, any flat variants are strictly verboten, nonconforming, etc. It is act

The socket in your example is Type F, Schuko. Those are only available in recessed form, any flat variants are strictly verboten, nonconforming, etc. It is actually another problem of the original article: It doesn't show and distinguish between recessed sockets and sockets that are available/allowed to be used in a flat form. The recess also makes the mechanical mating far more robust and takes away mechanical wear from the prongs. So in contrast to flat designs like the British, where all the force rests on the (admittedly thicker) prongs, Type F avoids that problem by distributing most of the forces into the socket housing. Of course you need to replace that if cracked, but you avoid the danger of cracks in the prongs. Cracked or bent prongs are really a fire danger because if they don't immediately fall of (which is the good case), they might continue to be used, albeit with increased electrical resistance due to the crack. Resistance leads to overheating, overheating leads to fires. And no RCCB/SRCD or OCB will help you there. An AFDD might (if there is an arc, which might be 50% of cases), but nobody has those because they are fairly new, very expensive and only code-required in some special types of buildings (care facilities, hospitals and such).