I had always assumed that eBay couldn't/wouldn't change their UI because their users are not techies and would be more confused by change than the terrible UI they've already learned. Users have learned how to do what they want, even if they don't understand why.
For example, my parents know that to watch DVDs, they need to press button X on remote #1 and then button Y on remote #2. They just don't know why.
I had always assumed that eBay couldn't/wouldn't change their UI because their users are not techies and would be more confused by change than the terrible UI they've already learned. Users have learned how to do what they want, even if they don't understand why.
For example, my parents know that to watch DVDs, they need to press button X on remote #1 and then button Y on remote #2. They just don't know why.