What I am not seeing on here is that a key reason for the granny charger saying it's for emergency use is because it doesn't have PEN fault detection which in certain circumstances (granted rare) could cause the car body to become live and would electrocute someone who touched the metal bodywork whilst a PEN fault was happening. This is the same issue why a basic "Commando" socket isn't supposed to be used either for fixed charging.
According to the IET PEN faults have increased by over 8 times since 2003, so this isn't an issue that is going away with time with around 400 reported instances per year (of PEN fault not electrocution via EV) and that's only what's reported.
Proper EVSE's are now required to have PEN fault detection, hence why they should be used for fixed installations, with all other methods being classed as unacceptable if they don't have PEN fault detection.