This issue was discussed previously in this thread:
https://vintage-radio.net/forum/showthread.php?t=159413.
The objection to the use of AC/DC receivers with half-wave rectification came from not from the local setmakers (some of whom wanted to go that way), nor from the electricity suppliers, but from the water supply authorities, who found that the resultant stray DC earth currents caused significant corrosion of underground pipework. This was based upon measurement, not assumption. The supposition that it originated as a non-tariff trade barrier is not supported by the available evidence. That argument seems to be commonly invoked in cases where the destination country regulations differ from those of an exporting country, sometimes I think before any analysis is done as to why there are differences. That regulations differ is hardly surprising. There are usually multiple satisfactory solutions to any given engineering problem, and that chosen will often depend upon local circumstances, preferences, etc. In some cases the differences might also turn out to be hurdles to trade, but that does not mean that they were originally installed with that intention. For example, the effective division of world electricity supplies into 50 Hz and 60 Hz areas is a barrier, although less so these days, but arose not because of a desire to create a barrier, but from the separate deliberations – and outcomes - on the question of optimum frequency.
Given that Australian electricity distribution coalesced on the MEN system, I think following the NZ lead, where it had been standardized in 1920, then non-negligible earth currents did exist as a matter of course, and I understand the more so with the commonly used overhead distribution. The MEN system, with a neutral-to-earth connection and earthing point at each consumer’s premises had been adopted with good reason, namely poor ground conductivity in many locations.
Whether or not the MEN system and its consequences, including the need to minimize DC earth currents - was idiosyncratic I think depends upon one’s frame of reference and comfort zone. From the UK perspective, it may well look that way. But turning the telescope around, I found that the UK use of clunky three-pin plugs incorporating fuses to be rather odd at first, until I understood the reasons – including the use of ring mains - for so doing. And I thought that the NZ earthing requirements were pretty strict, until I was living in Texas and had a house built. There its was required that just about everything, including the neutral, be bonded to the grounding stake, including incoming utilities (telephone and cable TV) and the TV/FM antenna structure and coaxial cable outer. One could have a separate RF ground stake for HF receivers, but it had to be bonded back to the main ground stake. One reason was that in an area of intense electrical storms, kV potential differences could exist between ground points separated by just a few metres. I surmise that DC in the ground currents was less of an issue because the split-phase system would result in much cancellation, even at individual consumer level, hence the acceptance of AC/DC equipment..
Cheers,