The biggest advantage PCGS has, is that they are photographing the coin outside of the plastic. I have no idea what Spink is doing (also out of the plastic), but their images are awful. The truth is clearly somewhere in between. It is clear to see that the coin as photographed by Spink had PVC residue, and Atlas/PCGS likely actually saved the coin from being completely ruined.
As for how PCGS manages to produce such "fantastic" photos, it is because they photograph coins, particularly proof coins, tilted into the light source. Thus, the surfaces are often completely blown out with light, hiding hairlines and other potential problems or things that a buyer would want to know/see. But, accentuating and overemphasizing color.
Phil Arnold (the PCGS lead photographer, who developed the TrueView service line) is mostly interested in photographing coins from an "artistic" standpoint. He wants to show them in their best clothes. For those of us who are also numismatic photographers, Phil's photos are known in the business as the glamour shots of a coin. They are flattering and often hide surface attributes, but they sure are "pretty" (if you collect photographs, instead of coins!).
Lastly, I will state that PCGS TrueView images are consistently and annoyingly red-shifted. They are not doing any "funny business" in Photoshop or in post processing (they have to photograph WAY too many coins per day to have time for that), but the lights they use and the white balance they use always shifts the colors and over-saturates the colors toward the higher end of the red spectrum. This annoys me to no end, and I have told Phil directly that it is not an honest way of presenting coins, but the opinion seems to be it has always been that way, and we don't want to change it now.
Sigh...