It's common courtesy and shows respect
Standing when the judge enters the courtroom is a sign of respect for the authority and role of the judge in administering justice. It is a tradition to show deference and acknowledge the seriousness of the legal proceedings before the court.
People are supposed to stand when any judge enters any courtroom; it is customary, and a sign of respect for the judge and his office.
Everybody is expected to stand until the judge is seated at the bench.
You stand whenever the balliff or court officer tells you to. Usually this is done when the Judge enters and leaves the courtroom.
It has long been traditional for counsel to bow to the judge when they enter the courtroom while court is in session and upon the judge entering the courtroom. The bow is not an exchange of courtesies between two duelists about to fight. The bow is a sign of respect. Counsel bow to the judge, not as a sign of respect to the person, but as a sign of respect to the judicial office.
Traditionally the judge would carry the Bible in with him and all would rise for the "Law" entering the room. Now days the judges like to think it is for their position; but technically judges are public servants and don't demand that respect. Now it is just tradition from a time passed.
Key parts of a courtroom include the judge's bench, witness stand, jury box, gallery for spectators, prosecution and defense tables for attorneys, court reporter's station, and the clerk's desk.
So the People will know who is the Criminal or who is the Judge talking to.
Reverend Sykes prompts Scout to stand up along with the other people in the colored balcony in a sign of respect for Atticus as he exits the courtroom.
standing mute means to not plead guilty or not guilty. In the United States when this occurs the judge will enter a plea of not guilty on the defendants behalf.
Stand and remove hats to show respect
In "To Kill a Mockingbird," the people in the balcony stood as a sign of respect for Atticus Finch after he defended Tom Robinson in court. It was a gesture of acknowledgment and admiration for his courage and integrity in taking on such a challenging case.
In Ireland students may be expected to stand up when a teacher enters the classroom. However, this is not true for all schools.