In the case of Star Wars it's partially on purpose. The space battles are modeled after WW1 dogfights, people use pack animals where cars would be much more useful, there is no paper, and light sabers are, well, self-explanatory. Star Wars is an adventure setting with a sci-fi theme, it's not a prediction of any kind of realistic future.
Star Wars contains many of the same "failures to predict" that Star Trek does, but if Star Trek had been thought up only yesterday they would have handled those things differently (like say more compact and user friendly or maybe even holographic data slates with more pictures and videos that don't look like an ancient brick next to a smartphone), while Star Wars could have chosen to still do things the same way because they like that better for their setting, for the retrocool.