Why was Britain unusual in building forward aviation support ships?

Why did other navies not adopt Britain's forward aviation support-ship concept?

Britain's exceptionally long Pacific supply chain rewarded forward repair, while the United States could rely more heavily on mass production and a steady flow of replacement aircraft.

The forward aviation support ship grew from a specific British strategic geography. Britain's industrial base lay half a world from the expected Pacific theatre, and disruption of the Mediterranean route could lengthen the supply chain around Africa. A repair-and-replacement ship close to the carriers therefore helped preserve air groups without waiting for aircraft or components from home. The United States faced a shorter trans-Pacific route and planned around mass production, making wholesale aircraft replacement more attractive than duplicating Unicorn's model. Shinano is treated as a late carrier conversion rather than an equivalent purpose-built support concept.