From: Winnipeg, MB
Most Australian and New Zealand units are assigned to "restricted" HQs and must be bought-out to an unrestricted HQ (this will cost political points) before you can load them on transports.
See manual p. 178f. Same restriction applies to air units.
The game prevents restricted units from boarding ships, but they can be flown out and on continental land masses can march across borders. In the latter case, most players self-impose rules that require the unit be bought out to an unrestricted HQ before crossing a border.
Because the game only charges ¼ as many Political Points to change to an HQ that reports to the same one as the LCU currently has, or IS that higher level HQ, players generally try to do this in the early game when PP are few and precious. 1 Australian Corps HQ is unrestricted (even though it reports to the restricted Australia Command HQ) so I change units to that HQ if I need to send them to Australian bases by ship - e.g. Port Moresby or Rabaul. This is in the spirit of not crossing national boundaries and what the Australian government might have done.
However, if I later want to assign 1 Australian Corps HQ to an unrestricted Command HQ like SW PAC or ABDA, I feel duty bound to also change all the LCUs to that same Command HQ (at full PP price) since switching the Corps HQ would allow all the units reporting to it to be unrestricted across national boundaries. This effectively slows down the eligibility of your LCUs to deploy forward, which is the whole point of the PP system and reflects RL pressures to keep troops in the homeland in case the Japanese come there.
There are some places on the map where national boundaries would not have been an impediment to movement of troops (the Canada/US border is one) so exceptions can be made to the border crossing rules for land movement.
No matter how bad a situation is, you can always make it worse. - Chris Hadfield : An Astronaut's Guide To Life On Earth