Not only is "you" the formal, polite plural form, but calling someone "thou" was also seen as so informal as to be rude (in verb form, to "thou" someone). This has a modern equivalent in the term "tutoyer" in French.
https://www.etymonline.com/word/thou
An interesting counterpoint is the usage in Japanese of sarcastically polite forms like お前 and 貴様, where you use a pronoun with a surface meaning of extreme respect, as a form of insult.