Its not about 'low numbers' for the last weekend of the event, it is more about them cashing in as much as possible. While halloween night is not the busiest night of the event it would be plenty crowded enough on its own. They just want to cash in as much as possible, it costs them nothing to allow the turnstyle computers to allow the FFP's in, so once again it comes as no surprise that they do this the last two nights of the event.