If it's against YA ToS to ask about suicide, post if you are under 13, and how to download pirated software, why aren;t they deleted?

They are either not reported or the reporters do not have a trust level that is high enough. Most likely, they are just not being reported which is required to get things started.

Because most people here have NO CLUE that this site is USER MODERATED and that reporting such violations is up to them and NOT YAHOO!!

Not if it is a knowledge based question like : What are the causes of teenage suicide?

no under 13s

Because either they are being reported but not removed or no one reports or knows to report those kind of posts.

Yahoo doesn't read or even actively scan posts here.

They'll act on a complaint or if you report a question but that's all.

Maybe reporter has low trust or not enough users report them