Concealed carry is not an option for many people: if you have a history of alleged crime yourself, if you live in states or counties that make that unreasonably difficult, or if you are entirely dependent on the finances and will of another person (try sneaking away for the required training and time to pass a background check when you're bordering on a human trafficking situation), it's effectively impossible. There's also wait periods. People have been murdered during cooling-off periods because they didn't have a gun until it was clear their partner wanted to kill them, but by then it was too late to wait 5 days. There's only so much the police can do about your intuition, or even a verbal threat.
Restraining orders also only stop people willing to respect them. If someone wants to commit murder, the idea of violating a restraining order marginally increasing the punishment and risk of capture changing their mind is a bit laughable.
It's a long answer to this, but I'd suggest people look up the "Wanted Podcast" episode 22 to understand similar situations better. It's 2 bail recovery agents telling a story of a skip they tracked down. She had missed a court date (probably because of her situation - being effectively forced into prostitution). She was in a terrible situation, but because of drug addiction and other psychological control in an abusive relationship, she couldn't bring herself to leave. She had called her parents for help, but then called back and told them to ignore it. One of the toughest people I've ever known hesitated to confront the man controlling her life. She had a phone at times, but it could be taken away by her captor, and when she had chances to leave she wouldn't take them. I doubt she specifically would use an app like this, but it's a case of not wanting to leave, being able to leave whenever she wants, but at times it escalates and she wants to leave but loses her ability to call for help.
It's irrational, but it happens to people.