A good makeup artist will make a wedding photographer's job easy, but not on purpose - in doing so, they make life easier for themselves too. I am of course talking about light!
The amount of light and the quality of light are not the same thing. Just because you have a lot of light, doesn't mean you have good light. Likewise just because you only have a little bit of light doesn't mean that you're in a bad situation. I would much rather have a tiny bit of good light than any amount of bad. This is always on the mind of any good makeup artist too.
Left to their own devices, a lot of people will apply their own makeup in front of any light source, but a lot of modern lights give off an orange-yellow hue. Getting your skin tone correct under this type of light is easy, but incorrect. People will compensate for the colour of light that they're in, meaning when they get into daylight, all of a sudden they're slightly the wrong colour. This is why a good make up artist will always apply make up in front of a source of natural light (or a daylight-balanced portable makeup light in winter.) And that's great news for wedding photographers as we just love natural light. Sitting a bride in front of a window not only gives you a good source of light, but the light is directional in nature too, much like a studio light would be. Because of the nature of this light, you can expose for the bride, meaning everything else in the image naturally becomes darker, which is the effect that you are seeing in the image above.