On an IT-network, where both lines on the socket are live, the GFCI wouldn't work on a single fault.
Which has benefits in in some high continuity systems (eg: operation rooms), a single fault doesn't turn everything off.
But you will need to actively monitor for single faults using insulation monitoring.
Instead, we ground neutral so that even on a single fault the protection mechanisms work. We call this a TT-network.
It has nothing to do with touch safety. SELV (safety extra low voltage 42V) is for wet areas and touch safety.