GreedBay is doing this to encourage sellers to offer free shipping. The few times that I've tried free shipping, I lost money. I was selling identical items with the exact same auction setup, the only difference was one had free shipping and the other didn't. The one that had free shipping got more at auction, but not enough to compensate for my shipping cost.
I was offering free shipping consistently on chainsaws. Always free shipping on small items.
The savvy buyer could see that I was selling an item at the same price as the competition, and they were going to save the shipping if the other guy was charging. This would allow me to build capitol faster.
I can see their point on this. You sell a chainsaw and want to save a little on fees...charge a higher shipping rate. Well, at least that's how it used to be.
Sometimes you would get a nut job who buys a $500 dollar saw for $250 and then he goes nuts if you made a little on top of the actual shipping cost.