I am not surprised, given the advances we've seen in airbag technology and the widespread use of pre-tensioners and force-limiters in the front seats that work in conjunction with airbags. All things equal, the front seat is more dangerous than the back seat, simply because it is closer to the point of impact in the most common and severe frontal crashes. This article illustrates that newer cars may more than offset the disadvantage of being in front with the use of advanced safety features for adults that are lacking in the back seat. Some cars do include force-limiters and pre-tensioners in rear seats, though this generally tends to be luxury and sport cars.
Keep in mind that some of those features that may be beneficial for adults can actually be detrimental for kids in child restraints. Airbags and force limiters come to mind. As Dillipop mentioned, the article does state that children are still safer sitting in the rear seat.