Because it shows the difference between a matte screen and a glossy one under the same conditions. The point was not to show which display is better. Its pretty obvious from a glance to understand what was being communicated.
OT: I've stopped buying glossy screens since about 3 years ago. As in, I wont even consider a monitor that has a glossy coating - especially for a laptop. For desktop monitors, buying a good matte panel then color calibrating will get you superior picture quality than an uncalibrated glossy screen, with the added benefit of being able to use it in a lot more positions. Even a table lamp a few meters away from a glossy screen can render is pretty much unusable, not to mention the hideous reflections you get when the screen is black/dark.
Hell, I even put matte screen protectors on my phone and tablet. Makes the displays actually useable outside and it just looks that much cooler.