You only give them the destination when you check out. They want to factor shipping into the price transparently from the start. GeoIP data is available from the very moment you load the webpage, your shipping address is not.
That seems odd because if I happen to be browsing from abroad I might be put off by the shipping costs, which would turn out not to even be accurate for the destination I want.
> They want to factor shipping into the price transparently from the start
I guess if they made it obvious that that's what they were doing (stating their assumption about your destination) it would be fine.
