Why not? It's a superb all-weather surface to ride horeses on and stays within the arena, not all over the land. Most all-weather surfaces are made from similar recycled products such as used car tyres, assorted fibres with oils added and so on. It doesn't freeze, isn't as wearing on the horse's hoof wall and gives good 'bounce' instead of jarring their legs like frozen ground or very dry earth. I can't see the problem myself.

(It is just the plastic, by the way, no copper)