From that picture it could be under taillights or through the blue grommets but not sure if they spent the extra time to fish it there. If you go through a heavy rain or wash your car have a look around the taillight for moisture to make sure it stays dry there. Running through taillights is the easiest way to install but will distort the taillight seal which may cause issues down the road.
yeah, Im glad you brought this up. Do you have any recommendations to help "seal" this from potential rain getting in?