Because most countries that have ballistic missiles have not fired them in real war scenarios recently, and if they have, they have definitely not done so with quantity. Iran is the main power that has frequently and effectively fired ballistic missiles recently. Pakistan, Turkey, Egypt, Saudi Arabia etc,. - they all claim to have BMs deployed, but when last did they fire them in real battlefield scenarios? Now when did they fire them against advanced western countries? We cant compare Iran's BM success rate against countries that have BMs but last used them was decades ago. Respectfully!