They use exclusive sections of an existing colo provider facilities, often called data suites or data halls at least in Australia, where the 3 AZs are split bet

They use exclusive sections of an existing colo provider facilities, often called data suites or data halls at least in Australia, where the 3 AZs are split between numerous commercial colo facilities. They get enough control through their contracts to make sure the hosting provider provides exactly what they need to spec.