They did. It was called the Computer Security Initiative. It was the culmination of efforts starting with Anderson Report that collectively invented INFOSEC and deployed high-assurance versions. Early releases were secure messaging, the BLACKER VPN, MLS endpoints, private databases, and so on. Industry ignored it in favor of cheapest, fanciest products with features moving at explosive pace. Congress's (or DOD's) COTS mandate and NSA's MISSI initiative finished it off by reducing government contracts for high-security product.

So, it's been done here before. It would work again. Just no will to do it on top esp with Microsoft and IBM's lobbying. ;) At least the papers on requirements and methods for achieving that were all published. Some still use the methods in commercial sector and CompSci. The first, secure systems are still available comnercially on not-so-secure hardware (i.e. Intel). Just almost no uptake in FOSS for such methods despite a labor advantage.