France is weird -- the lawless areas

America is scary and weird. France, however, is also very peculiar:

French Lessons

... The French equivalents of New Orleans's Lower Ninth Ward lie in 300 or more "zones de non-droit" (lawless areas), which sparked the national rioting. These are areas in the immigrant suburbs of Paris and other large cities where the police do not go as a matter of policy. They have instead for years established checkpoints on the perimeter of these islands of soulless high-rises and then let the inhabitants fend for themselves.

Don't go as a "matter of policy"? Good lord. Is this true?