Can someone please explain to me why this isn't a classic "correlation does not imply causality"? This is not a randomized trial, which means that if there is

Can someone please explain to me why this isn't a classic "correlation does not imply causality"? This is not a randomized trial, which means that if there is a bias of "better athletes spend more on their shoes" then it can also explain the 4% increase of Nike Vaporfly.