Unfortunately a lot of that is also open to interpretation.
Yes, that is correct. It is also why rarely in the US, is a person prosecuted for shooting an intruder. There is to much for the District Attorneys to prove, so they don't even try and prosecute.
How can they prove a person wasn't afraid.
Like 03USMC said,
Then it's up to the DA to formalize charges (meaning he charges what he thinks he can win)."
When the law says reasonable force, the prosecutor must prove to a jury made up of citizens, that the person only broke in to use the phone and wasn't really going to harm anyone.
The person in the home only needs to say "I was afraid he was going to kill me."
The prosecutor has to prove the person in the home was not afraid for their life.
In the case of shooting a rapist, the rapist could say, "I wasn't going to harm her I have a small d**k."
The intended victim could say, "I didn't know that, I shot it off while he was reaching into his pants."
The prosecutor still has to prove the person was not in fear for her life.
You could say the victims don't want to be arrested and go to jail for shooting someone. The victims would probably say, "Better that than being dead".
Also if you kill the person breaking into your home they can't testify against you.