Hal Ashby is considered by many to be one of the best directors in the New Hollywood wave of filmmakers that came onto the scene in the 1970s. Harold and Maude was his second effort as a director and we watch as a very specific way of seeing the world is put into frame through Ashby's lens.
Ashby has a very specific style and way of looking at the world that suits the characters of this film in their uniqueness as well. Tone is the main point that one should make when looking at this film. To be able to hit the mark time and time again is a combination of craft and gifting. It is something learned and toiled over and the ability to trust your instincts in combination with technical aspects of creating moments that thread together to create a whole narrative. One example of this is when Maude leaves the funeral after meeting Harold and she peels out in her Bug to do a u-turn over the curb and into traffic narrowly missing another car. This one moment tells us everything we need to know about "who" Maude is and it's done in a way that the moving image speaks louder than any words could ever do.
It's important to also note Ashby's influence on screenwriter Colin Higgins who was passed over to direct his own film on this project. Ashby made Higgins and Associate Producer on the project and told Paramount he would only direct the film with Higgins' blessing - and if the studio would allow Higgins to be on set with Ashby to learn from him. Ashby was setting up Higgins to succeed in an industry that can be considered very self-promoting, thus turning the norm on its head in order to help an up-and-comer. This is quite similar to Maude's relationship to Harold. A stretch? Maybe, but a viable one none the less.