Why Free Doesn't Always Mean "Free"

The word "Free" is sometimes merely eye bait marketing to encourage readers to take a closer look at a flyer, offer or advertisement. In the following offer a "Free" $500 Gift Card allows recipients to use the gift card to acquire sunglasses. There's a catch.

Here's a picture of the gift card, the card is designed to place more emphasis on its benefits than disadvantages with the words "Free", "$500", and "Gift Card" next to images of a pair of sunglasses and a watch. The other side of the card reveals the deal's caveats.

A close look at the back of the card reveals seemingly encouraging or helpful information reminding the holder not to lose the card and of its expiration date. A few lines into the small print it says "There is a 9% Service Fee to pay for the product delivery & handling expenses provided by our mailing company." If these were Oakley or Ray-Ban sunglasses a delivery and handling fee of 9% might be ok, but it certainly is not free when the gift card's balance can't be used to pay for the shipping and handling.

The prices of these seemingly 'expensive' sunglasses range from $90-$170 in the first picture with those numbers crossed out. The problem here is even though the sunglasses are 'free' the service charge is applied to the value of the sunglasses making 9% of $170 equal to $15.30 which might even be a multiple of the actual value of the sunglasses. When sunglasses cost a dollar at dollar shops what distinguishes these sunglasses from those?