LePereForeur
I’ve just researched this for you and found an article on The Verge that explains the tempering process that makes glass less breakable also makes the glass easier to scratch. Don’t know how reliable the information is, but I’m going to presume the frontside of phone (1) uses thinner glass than that used for the 7 Pro, and the extra tempering it requires is making the glass easier to scratch than that on the 7 Pro.
I recommend using a protector to prevent scratches.