You're not entirely wrong but I think that description of the situation is rather heavily colored by partisanship. Being lenient about a very limited subset of crime that "the system" is particularly ineffective at dealing with (to the point that it is arguably racist/classist/etc) is viewed favorably by certain (primarily urban) demographics. When you have broad support for an elected official who is exercising a great deal of discretion to not enforce the law that should trigger fundamental changes to the system as opposed to impeachment.