If on the other hand as others have indicated there no legal requirements for which pin the Hot and Neutral wires are terminated at, then that is a recipe for problems.
Why?
I believe that there must be some standard that electricians have to conform to and that the connections of sockets are clearly defined as to what each is supposed to connected to, so that anything that demands a ground connection for safety can only be connected one way when the plug is plugged in, so that the switch on the equipment and any fuse in the equipment is in the Hot or Live line so that in the even of a problem, the fuse isolates the incoming supply to prevent the metal work on the equipment remaining connected to the Live and still present a dangerous situation.
Here is a European tester
It's not mentioned that often here, but regarding circuit breakers / fuses there are significant differences between UK and mainland Europe.
I've read somewhere that UK uses up to 32A fuses for mains outlet ring circuits.
In Germany (and most other mainland Europe) 10A or 16A class B breakers are used for mains outlet circuits, and these aren't ring circuits, but rather star or bus type.
UK uses sometimes quite thin wires for their power cords, with a 32A fuse in the breaker board, it might happen the cord catches fire before the fuse blows. So placing a correctly sized fuse in the plug is a way to deal with this. As there's only one fuse in the plug, the plug must be polarized, otherwise a Live-to-Earth short still would burn the cord.
Here, there's no power cord using wires of less than 0.75mm². Shorting these wires at the end of a typical power cord (or inside a device) provides high enough short circuit current to trip the 16A B breaker, no matter if the short is L-to-N or L-to-PE. So no need for a fuse inside the plug, and no need for polarized plugs.
All the other stuff (ground fault interuptors etc.) was invented later and is for redundancy, as most of typical safety measures rely on redundancy. First level is the insulation. Second level e.g. is the earthed metal casing (or double insulation), a short from L to case will trip the regular breaker. Third level is the GFCI, if the earth wire is broken (which can happen and no one will notice), it'll trip if someone touches the case.
BTW - did you notice the European tester fits both ways into the wall socket. So if it shows "L / N swapped", just turn it around and it'll show OK. Still useful for checking, anyway.