Mirandizing is not "required."
Unsolicited, pre-arrest, un-Mirandized testimony is perfectly admissible.
The Miranda warning prevents a defendant from using the defense claim that he was unaware he was under arrest and subject to the different rules involved with having The State remove his freedom of movement, etc. It's a protection for the prosecution, but also a protection for the citizens against the state's use of ambiguity to conduct coercive interrogations.
It's more than just, "you expect me to follow all those laws but not to know a few rights?!"
Disclaimers: IANAL, and I wrote "citizens" but admit not knowing if that's too restrictive legally in the historical context or not. Guess I need a refresher :-)
Spoken like a true liberal.
I remember the Miranda decision of 1966, by the whacked out leftist, libertarian, Earl Warren court that Ronald Reagan and all other conservatives despised so much.
I was totally baffled by the Miranda decision and I still am, but it is another one of those 60s stunts that the left/libertarians got away with and Reagan’s attacks on the Warren Court helped win me to him.
In 1966 it was Miranda, in 1973 it was Roe V Wade, and 1965 was the Kennedy, “turn America into a third world cesspool legislation”, those were heady days for liberals, 180 years of history thrown away as “wrong”.