It’s “voluntary” except for all of the different ways it’s been written into regulations, from federal procurement all the way down to local government. But if

It’s “voluntary” except for all of the different ways it’s been written into regulations, from federal procurement all the way down to local government. But if the market prefers it, great! Do it without the need for a government bureaucracy! Organizations like Underwriters Laboratories don’t need an arm of the US government to exist.