If this was true, the Miranda rights would read something like “anything you say will be used to obtain justice” rather than “anything you say can and WILL be used AGAINST you.” The police and justice system are never your friend. They are always your adversary, and should be treated as such. Under a different regime, they could be your ally if you’re innocent, (and this is the case in many countries) but in the US, they are always hostile to everyone, including innocent people. Even if individuals in that system don’t fancy themselves in that light.
