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.
I do not follow.
To me, if you have a system that is dangerously less secure if phase and neutral are flipped, then that system is faulty and needs to be fixed. If there is a difference, but the security level with the polarity switched still is high enough to fullfill the requirements in law/other rules, then there is no actual problem. (Do note that we are discussing the system safety in normal operation, not split open on the bench.)
The cases you put forward, are dealt with by the PE conductor and/or the RCB, and it is therefore important that ground mates first, and that it breaks last. Such details are catered for in most well designed plugs and sockets. It is also obvious and fulfilled by all plug/socket systems we've discussed that PE must be unambigious.
Regardless of that case, since you can't safely rule out two different cases,
- Isolating centre tapped transformer or Delta supply
- flipped polarity
...any safe equipment must deal with full mains potential on both conductors of the supply in a way that's no less secure than the "intended orientation".
Issue is moot, and insisting is pointless. IMNSHO.
In any well-designed system / product, the switch should be on the live side. If the supply is reversed, either because the plug is reversible or the socket incorrectly wired, then there is an inherent possible danger with the equipment, whatever it is unless it's double pole switched or double insulated. You say that the PE should protect you, as you correctly say that is designed to be the first connection on the plug / socket to make and the last to break. But that is of little consequence if the PE path in the power cord is damaged or the PE house wiring is ineffectual. The RCB is only there as a back-up safety device, not a catch-all device to allow for shoddy workmanship in the wiring installation. It is also possible for some RCB's not to trip when they should and one cause has been found in the past with DC being leaked to ground which can saturate the RCB detection mechanism which renders the device useless. This is one of the reasons why they should be tested at regular intervals to spot troubles before they become major problems, much the same as fire alarms should be tested from time to time.
A fully qualified electrician should know the correct way to terminate sockets and make sure that their work is above reproach, it could be, after all, life and death consequences for someone later. If there are mains plugs around that can be inserted into a socket in more ways than one, then they should be removed from sale. That said, I have seen incidences here in the UK with 13A plugs inserted upside down, with the cables exiting the plug at the top rather than the bottom. This was on an industrial floor washer / cleaner, the type used in large department stores by the cleaners, and further investigation revealed the equipment had been badly abused, and the plastic plug top smashed on the floor a few times and the earth pin fell out. With most sockets this would have prevented the plug being inserted, but for a number of years we had a leading manufacturer producing sockets that only required the Live and Neutral pins to operate sockets shutters and thus allowed the plug to be inserted upside down
Given that the machine was a big heavy beast, with a cast alloy body, had a water tank that sprayed the floor in front of it and that the on / off switch was a single pole, it was fatal accident just waiting to happen. I had no option but to report the incident to the store management for them to take further action over it. I have since heard of similar cases back in the day when hand held drills used to metal ones, such names as Black & Decker, Wolf spring to mind.
Think about it, back then there was no such thing as RCB's, even mcb's were usually the domain of industry and commercial building if you were lucky, otherwise it was rewireable or cartridge fuses, and you had completely lost the added safety factor of the PE. Thankfully the maker of those sockets has now replaced them with a range that requires the earth pin to be present otherwise the plug cannot be accidentally inserted.