Oh! I've heard you should say "you too" not "me too" in this case. Can you explain why?

Native speaker’s answer
Rebecca
In the case, "you too" is correct because the "[good to see]" in "you too" has been omitted here. The speaker is returning the greeting by saying "you too." However, it can be confusing so it's better to say the whole thing, without omitting any words. Ex: A: Great to see you today! B: It was great to see you too. Ex: A: Have a nice day! B: You too.