I'm no fan of the movie and am not claiming anything on its behalf, but I fail to see how the above is in any way a valid criticism. All the writer's noting is that the world of Crash does not conform exactly to the world she lives in, the very fact of which is, apparently, an artistic flaw. While she's at it, she may as well condemn His Girl Friday because no one actually talks like that, and dismiss Hamlet because it's not an accurate representation of mediaevel Denmark.
Before I go off and say what I have to say, first let me also say I'm no fan of Crash. It does nothing more than beat you over the head with after school special style morals on a Hollywoody budget.
That said, the writer obviously did make an attempt to make a Los Angeles as he sees it, unlike a film like His Girl Friday, which like so many other great films, creates a universe onto itself. In a span of an hour and a half, we're introduced to Howard Hawks' world and are allowed to view it courtesy of the camera. Crash on the other hand makes a sad representation of L.A. with archetypes of the rich, the crooked cop, the oppressed black man, and the poor Hispanic in a convoluted melodrama. Seeing these people everyday as a Los Angeles native, their lives and personalities go far beyond what's depicted in the film, but the writer(s) have no grasp of them. It's pure Hollywood exploitation through and through.
EDIT: When I finished the post, Domino Harvey posted pretty much how I felt