It's absolutely crackers. I had a BMW sump to sell and when I listed it did so with £10 or £12 postage as I know that would be right for the item size and weight and to leave a couple quid for my materials.

When the item auto renewed it went onto simple delivery and ebay in its infinite wisdom decided it would fit in a medium parcel category but also that it weighed little. A buyer bought it and I had to explain the issue. I spent an hour waiting for a call from ebay and went round in circles and on hold trying to solve it. In the end I explained to the buyer who still wanted it that I would cancel the sale, relist the item and hopefully be able to choose a suitable service - still no - the arrogance that they think they know better than my scales and tape measure! In the end I have had to relist the item intentionally in a wrong category to get it over the line as it let me choose other courier 3 - 5 days and set my own price.

I have been using ebay to buy things I need and sell things I don't for 22 years, I never use the Bezos website but am really close to delisting all my stuff here as it's so frustrating and I bet this won't be the only issue with my currently listed 150 items.