Why these movies were every 70s child's worst nightmare?

horror films from the 1970s that millions of American children watched by accident — through drive-in theaters, late-night television, and gaps in parental supervision — and never fully recovered from. From a tunnel beneath London filled with human remains to a ventriloquist dummy that a television commercial had to pull from the air because children refused to sleep afterward, these are the images that arrived before anyone was old enough to process them and have never left.