Exempting cargo pilots from rest rules is a bit like exempting truck drivers from rest rules, and only enforcing them for bus drivers. When they crash they are equally likely to involve bystanders.

If you are tired you are tired. you cannot always just fall asleep when you want or be awake when you want to be thats just the way it goes.

I have always said the rules are written in blood and until a cargo plane hits a school full of children nothing will be done. The very sad truth.