Girls und Panzer/WMG

The Girls und Panzer Universe's Economy and Society
Empirically, the Girls und Panzer universe (or Japan at least) has loads of resources to throw around for purposes that would seem frivolous in our world -- see the converted super-carriers used as schools, the deployment of large numbers of tanks for a high-school sport, and the casual emptying, destruction, and reconstruction of towns to provide those tanks with play arenas. (Not every battle takes place in a town, but Oarai's first match, against St. Gloriana, was a friendly and was held in town, so clearly it's not unusual.) What's more, Japan considers it a matter of national policy to promote tankery, and considers a school's tankery performance as a critical factor in funding decisions. Families with strong tankery histories own Big Fancy Houses and hold great sway in these matters as well. This could imply one or more of these variously fantastic and terrifying scenarios.

Perhaps the GuP world has achieved post-scarcity, and can easily afford to build tanks and supercarriers if they feel like it. The major weakness of this hypothesis is that, even in a post-scarcity economy where resources are plentiful, land is still not easy to duplicate, so the enormous Nishizumi and Isuzu estates still need explaining. (Perhaps these families make their money in some other way, such as ownership of mineral wealth that is necessary to build tanks?)

Less lightheartedly, Japan may be benefiting from a massive military-industrial complex. As the United States did in our world, perhaps they emerged victorious and largely unscathed from a world war (or maybe even the World War II) and are taking advantage of the built-up industry with tankery.

Even less lighthearted is the possibility that this war is still ongoing (perhaps nuclear weapons have not been invented, and some other geopolitical changes occurred as well, such as a German victory or near-victory against Britain or Russia, or the fragmentation of the Allied and Axis powers, so the war has stalemated). In this world, the government uses tankery as a pipeline to produce talented commanders and tank operators, and likewise uses the school-ship concept to produce a strong base of navy personnel. The promotion of tankery prowess as being an essential element of Japanese womanhood and the recompensation for property damaged in tankery matches is all part of the propaganda. (This gives yet another spin on Shiho Nishizumi's behavior towards her daughters -- in this world, she would certainly have been used on the front lines for her tankery prowess, and may still harbor lingering trauma. Combine that with the nationalism necessarily enforced by this scheme, and she may have concluded that the best way to bring up her children in this world is to forge them into undefeatable commanders...by any means.  Abusive, perhaps, but it might be the only way she can think of to guarantee their survival through the war.)  Certain schools are groomed to adopt the cultures, practices, and weapons of the various nations involved to pre-train commanders for battle with or against them. As a flexible commander who is able to put together a strong army out of rookies, devise strategies and emerge victorious against opponents from every 'nation', and then turn around, forge an alliance out of all of those nations at once, and defeat an elite university team, Miho will surely be a prized asset when she graduates. She may be in for some heartbreak...

(This would also lend some Harshness in Hindsight to Kay's comment that "this is tankery, not war", and the relative lack of men in the cast.)