Movie Memory

I was thinking about how memory is depicted in cinema.  In order to distinguish a recollection of memory from every other scene the film is usually somehow altered, made blurry, or shaky (aka flashbacks). I thought this was interesting because this method correlates to the idea that memory is fallible and changes when we try to recollect it.  Why can we accept that recollections in cinema can be altered but our own memories are not fallible?
http://www.phantomladyvintage.com analyzes the use of flashbacks in film noir.