Regarding tu/vous and formality in English
In English I almost always drop titles because they are hierarchical.
For instance, I like Patrick Stewart but I would never call him "Sir Patrick Stewart." And in the USA, I don't like "Senator So-and-so," just "So-and-So."
So probably if I were french I would offend people in a similar way but I don't understand how and I want to be nice to all of you in the sabbath :D
Thanks for all the explanations :)
@aprrrl On the internet it’s okay to use tu, and seriously I don’t think people would be offended anyway by using tu.