Kind of, but the legal system is tilted to prevent people from being unjustly imprisoned, not to ensure that every guilty person is locked up. Prosecutorial discretion and the grand jury process is part of that, but there is always a regular jury as a check to determine if the charges should be dismissed and the "default" if no one does anything is always no charges.
Now, its fair that in practice this can be abused to protect people in power by not charging them, or to get people deported by charging with things no jury would convict on, or scare them into a plea deal. But that is where the political system is supposed to step in (most DAs are elected) and remove prosecutors who are making decisions the voting population doesn't like.
But people don't vote (or don't research or don't care) enough to be an effective check on the legal system like that, which is a whole different set of problems... but my point is that these systems are designed to balance each other, not so that each system is perfect by itself.