I guess because the almighty DMV handbook says that it must be so. You pass the tests, don't break the rules, and it's your right. You don't have to go to the DMV with your hat in your hand and say "Please, may I have the privilege of a Drivers License?" then go sit in the corner like a little mouse with a piece of cheese while they decide. You have the right to come and go, and if that involves jumping through a few required hoops then so be it, but you don't have to thank anyone for the privilege.
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