French doesn't capitalise its formal you (vous). We're rude, never forget that !
Interestingly, it is not uncommon to capitalize you formal in Italian (Lei). I think the reason is that "lei" is also she, so it is done to distinguish the two.
If I'm not mistaken, Usted (Spanish you formal) is also capitalized, but I could be wrong. It might only be capitalized when abbreviated (Ud. for usted, Uds. for ustedes).