It bears the hallmarks of a classic urban scourge: back-channel sales, assaults on enforcement officials and even death. It is the price of parking in San Francisco. Burdened with one of the densest downtowns in the country and a Californian love for moving vehicles, San Franciscans have been shocked in recent months by crimes related to finding places to park, including an attack in September in which a young man was killed trying to defend a spot he had found. More recently, the victims have been parking control officers — do not call them meter maids — who suffered four...