Nobody even knows who S.H.I.E.L.D. is. o.o I dunno about X, but the way I see it is the motto being "What happens at Xavier's stays at Xavier's." What are the police needed for? These guys have superpowers and can definitely handle their own or find someone to do it for them. Calling police the handle a mutant domestic issue is like calling a rabbit to help a wolf. I personally don't know about the other teachers, but Art will be known as the most informal teacher ever. Xavier's, to her, isn't just some boarding school. It's home. So, that's how she acts about it. Plus, she feels that if humans don't want to give mutants the same basic rights, mutants shouldn't have to adhere to their laws lol.