You claimed that no one testifies because they would gain immunity. Pointing out that anyone can sign a waiver and testify. Your anecdotal evidence is worthless. Plenty of defendants and potential defendants sign a waiver and testify. And understand, on a Grand Jury OR a Petit Jury, you and see and hear what they allow you to see and hear.
Totally agree with you on the fact that they only allow you to see and hear what they want you to hear.
The murder case in the home much background info was kept from us to not sway our decision..
Afterward the DA told us the back story.