I am not a teacher but I did have a volunteer role that required a background check and training. I think it is standard now for all such roles- scout leaders, youth group volunteers etc. They wanted evidence from all countries of residence. I had to provide all previous addresses in all countries I had worked in, it was not related to working with children, just that I had no criminal record anywhere. I have no idea if they check arrest records etc (never have been!).
How the abusers involved in the church continue in role, I have no idea. There are clearly loopholes.
https://www.bbc.co.uk/news/articles/cp8nk5gvk4yo