Scare the kids films, also known as FUM for kids, are ‘80s movies that have given us Adults nightmares to this day, from films that were thought to be for kids. Film studios, even “Disney”, didn't really know what they were doing in the eighties. Thus the rating system had to be redefined by the nineties. “PG-13” was being fleshed out after 1985. A very clear [PG-13] rating won’t be seen until 1990, then was retrofitted to the older movies when they were shelved for Block Buster.
Believe it or not, Critters 1 and 2 were not [R], and Poltergeist (1982) was and still is [PG].