Some people probably do count them. It's just that most don't because the rides were obviously built as a free-fall ride and not as a coaster. The Frequent Faller was designed and envisioned to be a roller coaster experience. It's the same deal as the Journey to Atlantis rides at the Sea World parks. Because they have sections of coaster track, some count them but because they were built as flume rides, some don't.
