The term “meter-maid” was largely unknown in the UK prior to the song’s release. It is American slang for a female traffic warden, now officially known by the gender-neutral term parking enforcement officer. According to some sources, the song originates from when a female traffic warden named Meta Davies issued a parking ticket to McCartney outside Abbey Road Studios. Instead of becoming angry, he accepted it with good grace and expressed his feelings in song. When asked why he had called her “Rita,” McCartney replied, “Well, she looked like a Rita to me” – From Wikipedia. Because I’m lazy.