I have included the cars and people to illustrate the magnitude
LET THEM EAT CRACK is a political statement by banksy about how coldly the corporates in America treat everyone they are symbolised by the rat with the neck tie holding the breifcase
the text has ben written in blood and there is blood on the hands of the rat (corporates).The rat also shelters himself with an umbrella which I beleive is a comment on the bush administration bailing out big corporations in the US effectively insulating them from the reccesion.
It is obvious that banksy has alot of contempt for corporate America.
the money falling out of the breifcase suggests greed.An interesting fact I found out is that rat is also an anagram for art.