You have just perfectly articulated my position on this point. We SHOULD be buying our platforms from efficient, stable production line facilities overseas and joining global supply chains to provide efficient local support, repair and upgrade capabilities and chasing manufacturing opportunities where efficiencies of scale can be achieved across global fleets.
Which we actually do in many platform fleets, including the M1, the ASLAV with the GD turret facility in South Australia, JSF, P-8A and undoubtedly we will on the LAND 400 vehicles.
However there is a massive exception to this for some reason when it comes to the Navy. Our capability acquisition problems are the same, limited funding available to be spent on a relatively small fleet, but the difference is the apparent political imperative that supersedes these issues. Then for some reason we have to overspend by huge amounts of dollars, with usually huge project delays only to gain a similar capability or less, to what we would if we simply bought from existing production facilities...
As for MRH-90 and Tiger, remind me how we acquired them again? We ‘made’ them in Brisbane from recollection... I recall it pretty well having visited those actual facilities during the build phase... Once again to huge additional cost and schedule delay and all for only a temporary increase in manufacturing jobs provided. Then of course you add contractor incompetence, deliberate under-bidding and all the other problems with those platforms of course, but those are separate issues we have covered at length before.
Quite a bit of an apples to oranges comparison IMO with respect to armoured vehicles for Army vs. vessels for the RAN.
From what I recall of discussions when I first joined DT, an armoured vehicle production line needed to build into the thousands of vehicles to reach the point of viability from a cost perspective. Realistically, out of the five modern MBT programmes in the West, only the US M1 Abrams and German Leopard 2 reached production of that scale. The French Leclerc came close to 1,000 units (~850) but the British Challenger 2 was only ~450, while the Italian Ariete was only 200.
Australia might have reached that economically viable point (after a decade or more) with the Bushmaster with ~1,000 units ordered, though I suspect that the simpler overall design and lighter weight of armour would be primary drivers for that, rather than just raw numbers. After all, a smaller vehicle, with less need to cut/form armour, would require less tooling to be set up.
On the naval construction side, due to the time it takes to construct a single vessel like a frigate or destroyer, studies have been commissioned which indicate that a domestically built vessel with 30+% higher price than a foreign-built vessel, would still be competitive due to that funding going back into the economy. Purchasing raw mats from domestic suppliers, paying domestic yard workers for construction and assembly, and then the secondary and tertiary spending as the suppliers pay their workers, the yard workers purchase their necessities and commodities, etc. And then of course there is the benefits to ongoing and future support for that and other vessels by having both the facilities and personnel appropriate to working on a frigate.
The main issue that I see impacting production costs for some of the naval programmes is that gov't is inconsistent on placing build orders, alongside pollies trying to direct as much of the work as possible to benefit 'their' constituents, as opposed to placing orders to benefit Australia as a whole.
The selection of then-ADI's Bushmaster produced in Bendigo vs. Tenix's Unimog-based S-600 is a good example of politics driving procurement decisions. The S-600 was of equal or better performance in terms of mobility, protection, etc. As I understand it, there were two major differences, one being based that off the Unimog, a number of mechanical parts could be sourced from the worldwide Unimog customer support base which would reduce the likely repair and support costs, especially if operating away from Australia. The second difference IIRC was the one which led to the Bushmaster being selected, which was the S600 production site was in a seat firmly controlled by the Opposition, and there was no political advantage to be gained by the governing party, whereas Bendigo was in a threatened seat.
Playing the "what if..." game, I cannot help but wonder if the S600 would have had greater export success than the Bushmaster has had so far, due to likely lower support costs for foreign operators due to similarities with commercial/civilian Unimog mechanical components. As it stands now, it seems that the ~120 Bushmasters owned/operated outside of the Australia & the ADF were drawn from ADF stocks and then replaced. Meanwhile Thailand is producing an MRAP with Malaysia starting licensed production of the Thai design, and the Philippines had ordered the design and then canceled the order due to budgetary reasons. That strongly suggests to me that there is still a need for MRAP IMV-type vehicles, at least within the ASEAN region, but it is possible that decisions made for domestic political advantage might have contributed to make international exports non-competitive.