I personally have only seen children as passengers on that particular bike. But I just took a look at their product page and there are a couple of pictures with
adult female passengers. Yes, they are sitting low with respect to the rider, and for a very good reason: unlike a tandem, on a cargo bike the passenger is load. You want your load low and centered so you can throw the bike left and right as necessary. A higher seating of the passenger will greatly compromise maneuverability. Unless, of course, you size up the entire bike to suit. Is there a particular reason for choosing the compact design?