Humans constantly monitor their environment, and tend to only become conscious of something when it is behaving differently than it had been. Think of long drives - unexpected motions, odd noises, etc. trigger conscious attention.
Computers, especially of the 'cloud' variety, lack the incidental physical environmental interactions that give us those, so intentionally building them in is required. (And because they're intentional and artificial, they're at risk of manipulation, something else to worry about.)