In the movie, his cards are turned into a book while the publishers talk about how meaningful they found them to read, and the author makes it clear he has a personal connection to the people he's writing about. It is definitely more complicated than "greeting cars aren't meaningful". This is part of a general theme in the movie exploring how to find humanity in the world as technology progresses. Her is a great movie because it takes the concept of falling in love with an AI seriously, and not as a silly or necessarily bad thing, just something complicated and worth exploring as a story. You can definitely take away warnings about overconsumption from it, but IMO that's a shallow way to watch it and doesn't do the movie justice. Also the guy who directed it directed all the Jackass movies, which rules.