Every state in America (to my knowledge) has required Hunter's Safety courses. Almost all require blaze orange during firearms seasons. There are still fatalities, probably in every state, certainly in most, every single year.
....and while in these states, proof of that HS course must be shown to buy a hunting license, many poachers don't bother to buy a license. No real need as long as your breaking the law anyways. Responsible gun owners take gun safety courses and learn how their firearms operate safely. Making them mandatory in order to purchase a firearm would only makes those criminals that steal firearms or buy them on the black market guilty of another crime.