How do I sell on amazon?

Why doesn't Amazon pre-populate the weight field for a product I sell through my Amazon seller account, if they also sell it and presumably know exactly how much it weighs?

• About once every three years I sell something on Amazon. This time it was a game someone gave me that I knew I would never play. Although it was brand new and sealed I listed it at a nice discount to Amazon's price for the exact same thing, and a few hours ago I got an email from Amazon informing me that someone had bought it. I thought I'd try using their "Buy shipping" functionality because that would spare me the trouble of having to weigh the thing, but I had to weigh it anyway, because the weight field was blank. Wouldn't this be a trivial thing for Amazon to fix?

• Answer:

  It really wouldn't, because packaging doesn't all weigh the same, nor are they all sized the same. A USB memory stick could be 100g and measure 5cm x 2cm x 2cm, or it could be 200g in a giant plastic clamshell and measure 20cm x 20cm x 5cm. In my experience working at Amazon, with multiple vendors and merchants, people often sell the same things packaged in *wildly* different ways. Making assumptions about how a seller has packaged the goods is one of those thing you discover to be Really Bad Ideas(tm).