This actually shows that is it you who does not understand how global ilumination works. The amount and location of light and shadow depends also on the materials. You cannot compare the reflection of a corner in some random dude's house and the one in the Nvidia demo, because you have no way of knowing if the materials are even remotely similar, with similar luminance etc.
Look, I know you're getting egged on by some other users right now. So I'll try to cut you some slack here.
Let me just give you a few links on this issue:
Ambient Occlusion is a sophisticated ray-tracing calculation which simulates soft global illumination shadows by faking darkness perceived in corners and at mesh intersections, creases, and cracks, where ambient light is occluded, or blocked.
There is no such thing as AO in the real world; AO is a specific not-physically-accurate (but generally nice-looking) rendering trick. It basically samples a hemisphere around each point on the face, sees what proportion of that hemisphere is occluded by other geometry, and shades the pixel accordingly.
PxrOcclusion is a non-photorealistic integrator that can be used to render ambient occlusion, among other effects.
Ambient occlusion is an approximation of global illumination that emulates the complex interactions between the diffuse inter-reflections of objects. While not physically accurate (for that use full global illumination), this shader is fast and produces a realistic effect.
All three 3d programs above are Raytracers, implementing raytraced ambient occlusion. All three claim that the effect is "fake" to some degree. No one who knows what they're talking about would ever claim that ambient occlusion is physically accurate.