It is federal law that you cannot be given contact lenses without a valid prescription. Contact lens prescriptions, according to federal law, only last one year.
No, you cannot "OD on a contact." We know that. But it is still a prescription device that comes into direct contact with your eye.
SERIOUS SHIT can happen when you wear your contacts incorrectly. If we give you contacts when your Rx is expired and you come back with a scratched cornea and an ulcer that cause you to lose your eye (YES THIS IS POSSIBLE, dumbass) that would be all our fault because we broke the law, and people would lose their licenses and it would be very, very bad for all of us.
So no, we can't "just" give you contacts, any more than we can "just" give you, say, a pacemaker.
PRESCRIPTION DEVICE, people.