Why aren't motorcycle tracks designed with softer road materials?

Softer materials would wear quicker. Higher friction is necessary for tyre grip, a smooth track would be dangerous. Astroturf would be way too soft bikes would carve huge grooves powering out of corners.I live in NZ where we have just had a brand new international cl track built. They did a lot of research into surfaces and chose a new blend of blacktop specifically designed for racetracks. There is always a compromise to be made between track wear tyre wear and grip. Am I colour blind or just not observant I don't recall seeing a white track.