I guess the plural in some languages is used to address royalty. And about the usage of "they", I tend to use it, and the only thing that I find a bit strange i

I guess the plural in some languages is used to address royalty. And about the usage of "they", I tend to use it, and the only thing that I find a bit strange is sentences like: "If a user needs something, they have to do something." Note "needs" and "have" for the same subject, where usually they are either needs+has or need+have.