It is easy to sneak a back door into a complicated mathematical algorithm. Most people do not understand how it works anyway. And as we know it does happen on an epic scale, from many sides.
But there are impregnable physical laws, which all people understand. Still this type of security is neglected by hardware producers. For example, why there is no a light physical plastic lid, which can be used to close web-camera on a ultra-book physicaly? Why the web-camera lenses are always open? Why people shall use a messy scotch tape to close it? Or rely just on a dubious software security.
Why where is no a similar lid to close a microphone and a web-camera on a smart-phone? If a web-camera is closed by a physical lid it is closed. This is it. And it is not difficult to make a convenient design so that it is opened and closed easily.