I've always seen this as a tacit acknowledgement of how the justice system actually works. The cops know that if you have the money for a good lawyer you have

I've always seen this as a tacit acknowledgement of how the justice system actually works. The cops know that if you have the money for a good lawyer you have a much better chance of avoiding punishment regardless of the facts of the case. If you need to increase your conviction rate the best way is to go after people who are going to have to use a public defender even though in terms of actual damage to society the rich offenders are far worse criminals.