Why doesn't Boo come out in To Kill a Mockingbird?Was he being abused? Why didn't Cal like Boo's father? Should the neighbors have done anything to help Boo lead a more "normal" life?
Boo doesn't come out because he doesn't want to come out. His life experience tells him that the world is a scary, hard place. He was also shut inside by his father after a violent incident. His father is now dead, but his older brother is still domineering.
When he is around people, Boo is nervous and awkward. Scout says:
Every move he made was uncertain, as if he were not sure his hands and feet could make proper contact with the things he touched. He coughed his dreadful raling cough, and was so shaken he had to sit down again. His hand searched for his hip pocket, and he pulled out a handkerchief. He coughed into it, then he wiped his forehead.
A lot of Boo's fear comes from his family dynamics. His family is isolated and unusual. They don't spend time with their neighbors, and they don't open their doors to the community on Sundays. Growing up in such a way shaped Boo's impressions of the world. It likely didn't help that Boo stabbed his father and was locked in the courthouse basement as a result. This probably also helped to make him afraid of the world.
Whether Boo's father did something to provoke him is left for the reader to decide; Calpurnia does call him the meanest man alive, though she doesn't say specifically why. Scout notes that it's strange for Calpurnia to comment on what a white person like Mr. Radley does.
Whether or not the neighbors should have intervened is more of an opinion than a fact. However, it would have been kind for them to have helped Boo out, especially when he was younger and less capable of doing so himself. Even though it seems like Maycomb is a friendly place, no one was ever able to help Boo have a better life.
Arthur "Boo" Radley had gotten into some trouble with the law as a young man and, rather than him serving time in jail, his father agreed to deal with the situation himself. His solution was to restrict Boo to the Radley house. We can assume that this social isolation caused Boo's emotional problems, and he became a recluse within his own home. He apparently only ventured out at night when no one could see him. He may not have been physically abused, but the emotional abuse perpetrated by his father no doubt contributed to his deteriorating mental state. Calpurnia called Boo's father "the meanest man alive," at least in part because of his treatment of Boo. Mr. Radley was also a strict "foot-washing Baptist," and he was considered a bit too high-and-mighty by many of Maycomb's citizens. The neighbors stayed out of the Radley's personal business, probably in part because many of them feared Boo. Some people, such as Atticus and Miss Maudie, knew better, and remembered him as a decent person before his forced isolation.