It's not selective enforcement AFAIK. It's complaint-based enforcement. Analogous to neighborhood crime. Most of it will never be acted on because the cops are too busy, there aren't enough personnel, and they never hear complaints about most of it. Like in the U.S., where about 6% of the population is in the criminal justice system at any given time. It would be more like 30-40% if there were 1000% more cops/DAs/judges and every crime was followed up.