The deterrent we employ in this country (and almost all other civilized countries) against criminality is arrest, followed by prosecution, leading to fines, jail time etc...
This is what prevents most people from committing crimes, we do not want to have to suffer the consequences that would come for committing said crime.
While it maybe true that the initial "fear" (if you want to call it that) may be about the police themselves and getting caught (Run, it's the Rozzers!!!) ultimately they serve a pretty small opening section of the whole gambit and are in many cases effectively the "messenger" for the beginning of bad things.
The idea that you should fear the police, rather than fear the consequences of your actions is fundamentally stupid quite frankly. The police arrest you and collect evidence against you, but it is the court system that doles out the punishment and as such it is that which should be feared, not the copper arresting you for breaking the law.
You seem to have this notion that criminals should cower in fear of a police officer in case they get a swift beating, rather than fear the prospect of facing (potentially) years in prison for their actions.
Or to put it in a more succinct way...