The problem with banning these is that most of the time, the victims aren’t being forced to go to these places. Adults are talked into it using whatever religious shaming bigots can come up with.

When it comes to kids, you run into the issue that kids don’t have a say in their own lives (they do have rights, but they can’t easily exercise them). You can ban discrimination based on sex or gender, but you can’t easily interfere with a week-long church program for troubled youth. The state doesn’t get to dictate your religion.

A significant portion of just about any country on earth is grossed out by the thought of homosexuality. For a large part of voters, being gay was still a crime back when they were young. Things like gay marriage are still hot topics in the EU today. On the scale of centuries of backwards abuse and scapegoating, gay rights have moved forward at lightning speed, and it’ll take a few generations for those advancements to solidify (or, in case of the US and UK, lose decades of progress to hopefully regain them in the future).

Also, leeches are still used in medicine today, as well as ants, worms, and maggots. Not to cure the flu (unless your flu symptoms are the result of extreme iron consumption, in which case bloodletting is still necessary and leeches may keep blood flowing while doing that).