two tier law?
First of all: being arrested does not mean you are a criminal. Being charged does not mean you are a criminal. Being GUILTY makes you a criminal.
Somehow our society seems to have associated arrest with criminality (maybe from the "no smoke without fire" attitude, or maybe because the police treat everyone they come into contact with as a criminal - unless they can prove otherwise), which the fuzz not exploit to the full extent of their ability. So while we have a long standing history of law-making, with over 5500 statutes on the books there is another, undercurrent of law-making with no burden of proof, no protection for the innocent and no oversight or review, namely "Have you every been arrested?"
This level of policing is much easier as it has far fewer overheads, none of that pesky "due process" nonsense, no having to explain to a judge why you detained a person. Plus the always-present threat of "do what we tell you, or we'll ruin your life". This is much closer to the wild-west form of justice, or of knights of olde England who were trusted with "the right to bear arms and mete justice" with a similar lack of control.
Maybe what we need is some public awareness that the police do not have the right, nor the ability to label a person as a criminal just by arresting them. Only once the legal process has been applied and guilt proven, can a person be discriminated against. Not on the say-so of some plod with a bad attitude.