Fun fact: the track looks white because this isn't actually a photo of the wider area, but several extremely narrow photos (slices) of just the finish line, from different points in time, composed together. The ad behind there's is only visible this way.
It's also why the the athletes look slightly weird, as it shows what position each part of their body was while crossing the finish line, so at (only slightly) different times and their position has (marginally) changed.