Grammatically, there is no difference between "write me" and "type me" but tradition requires that they be treated differently. The reason for this is found in the long history of letter writing. Writing letters used to be the main way people communicated. It used to be that in order to say something to someone, you needed to send them a letter. For that reason "write" behaves a lot like "send" or "throw":
"write me" "send me" "throw me"
"write a letter to me" "send a letter to me" "throw a ball to me"
"Type" follows a different tradition. In our minds, it is not connected to the idea of sending. It is only connected to a mechanical process of punching keys on a keyboard. If you said "type me", I would be confused and ask you "what do you want me to type?". If you said "type me an email", I would understand what that means, but typing is a mechanical chore so it would sound less friendly than "write me an email".