Because it's a dirty method to get better than the competition. It's not as if they are making an offer every once in a while, they almost always have something to celebrate, and so almost always have free shipping. Most Elbox related items I've seen in the past few months have to do with free shipping.
It's not illegal in Greece even, it's on a borderline Telemarketers use all the time (eg. call during 15 minutes and the item will be shipped for free. Message repeated every 15 minutes;-))