And consider the light quality and the light direction.
She is underexposed. The white mustang in the background is way over exposed (blown out/clipped/no detail) and from a lighting perspective has the most visual weight in the image.
The brightest thing in a photograph generally is what first draws a person's eye, and become the primary image subject.
When a subject is backlit, like she was, flash is often used for fill.
Plus using flash lets us reduce the background exposure.
The way we do that is by using a faster shutter speed to give light from the background less time to fall on the image sensor.
When we use flash, the short duration of the flash takes over the ability to stop motion that we usually rely on the shutter speed to do for us.
It's a technique known as Dragging The Shutter.