More people don't call hotlines because they, and in I don't want to speculate the specifics, probably just need someone to talk to and aren't prepared to initiate an attempt as soon as that call is over. But They know what happens if they call, police wellness check, psych ward maybe, that screws up your job, family, etc., which I feel do the exact opposite of their goal.
They put you in a space worse than some minimum security prisons, and the only thing you have you do is to think about what you did watching a clock. Which is about so bad; you don't want to get better but just constantly planning the entire time a more lethal/foolproof method because you sit looking at that wall to a point that you're lesson is to make sure you succeed rather than the end up back in that hellhole.
I had the worst case, It made me at times want to push the doctor to the ground and punch him to see if I'd go to county jail, I'm in no way a violent person, but I honestly considered it to get out of there that's a possibility I where at least I could breathe actual air; but what ever cocktail of meds they gave me gave me nightmare hallucinations of snakes attacking me. I explicitly told him what he gave me had caused serious problems in the past, ignored me and said take the pills or you stay longer. I eventually just faked taking them then in a day then felt like I was in control of my brain. Most people could use a person to talk to and not take the risk of calling the number.