I'm very confused as to why you keep equating tears/damage due to childbirth with tears/damage due to anal sex.
Yes childbirth is risky. It can't be made safe. However without childbirth the human race would die out, and as animals we have an innate drive to reproduce. Not having children is not a feasible solution to childbirth injuries.
Anal sex is something people choose to do - we don't have an innate drive for buses. Educating people to avoid anal sex as a way to minimise risk of anal injuries has no effect whatsoever on the human race.
It's very interesting that the discussion is about "shaming" and how much fun anal is.
It's arguable how "fun" anal actually is given as stated upthread not that many people do it. In any case though, lots of harmful activities are fun- that's why people do them even though they are risky. I'm interested as to why we think we should educate teenagers about how to enjoy risky sex "safely" - it seems different to other high risk activities.
So for example, we don't educate teenagers on safe ways to procure and take heroin. That's fun though, and people use it so the horse has bolted. If we advocated the same approach you are suggesting for heroin as anal, we'd educate children how to take it safely and make it their lookout if that went wrong.
We don't educate children how to minimise the risks of smoking - we tell them smoking is harmful and to avoid it, we make it difficult and prohibitively expensive to smoke. If we used the approach you advocate, we'd tell them they could die of cancer but not increase the price of cigarettes and slap graphic warnings on the packets to make them ashamed.
You can tell children things are risky, harmful and best avoided without "shaming" them. We do it all the time for lots of things, why is anal different?