The term non-refundable only applies if a client cancels your booking. These non-refundable deposits exist because sometimes you will have to pay in advance some charges (travel expenses, materials, etc…). If a client cancels, you will be able to release this deposit from the escrow account, regardless of the cancellation policy. Non-refundable deposits are paid together with the balance payment, 3 days after the event date.
If you cancel the booking or do not show up, the client will however be entitled to a full refund.