Tire tread is kind of a dangerous measure; you don’t necessarily want everyone switching to a super hard tire. Basically you can trade tread wear for stopping distance.
Tire tread is already something that is measured on the books legally speaking but is never enforced really as such. You do need to legally maintain tread. As far as compounds go once again that's something that regulation can enforce. I don't think today that people are buying hard tires that are apparently too hard for the purpose of getting less wear out of them.