One detail in the worldbuilding of Back to the Future Part II (1989) that is often overlooked: the police department of Hill Valley in 2015 seems to be made up of statuesque women. And no, it wasn't just the two cops that found Jennifer on a bench and took her home; every time we see a police officer in the background of Hill Valley 2015, they were female.
This was a prediction that did not come true: women only make up 12% of all police officers in the United States today.
However, I can see what they were thinking with this. Consider that it was extremely rare to have female police officers in American cities before the 1970s. So, anticipating the entrance of women into police work, Bob Gale and Zemeckis might have foresaw a future where women make up half of all police officers, or even a majority. There are many examples of professions that were once majority male but over time, became majority female, like primary school teachers and pharmacists. In some countries, like Russia and Cuba, the majority of medical doctors are women, for example. Gender-based shifts in professions happen all the time.
The novelization of Back to the Future Part II gives a bit more information. According to the book, police departments in 2015 are majority women because it was believed by city governments that women's nurturing nature made them more likely to be caring, and less likely to be violent or brutal.
Fun fact: the woman who played the blonde cop was Mary Ellen Trainor, Robert Zemeckis's wife, best known as the only person to ever be in both The Goonies and Monster Squad, and she played a Mom both times. Mary Ellen Trainor also introduced her husband's friend, Spielberg, to her best friend, Kathleen Kennedy, who became Spielberg's most frequent producer-collaborator (Kennedy produced E.T. and the Back to the Future movies).
