There is a feature in UAC that is called ValidateAdminCodeSignatures. It is off by default and when on it prevents elevation of unsigned programs. The problem with malware (mis)using signing has reduced trust in this feature (but it is still very effective). This trusted source is the next generation version of it and it also suggests that Microsoft store apps are 100% to be trusted. Imagine a smart screen protection based on this feature would effectively bring white listing to the masses.
The "trust everything viewed as innocent by the cloud" idea seems to be more and more common these days. That is not whitelisting in my book.
