Can someone please explain to me why paying an unbinding fee is mandatory if the seller should already have the object/material upfront prepared for the consumer/buyer?
If you're selling something... aren't you expected to have the unbinding fee sorted out? There should be no point in selling if you're asking for the unbind fee + the cost of the item.
Most people who are asking for an unbinding fee along with the item usually do not have enough money to afford the cost of the unbind. Typically I see this happening with players selling weapons, and I myself have done it a few times. That being said, a lot of players wanting to buy your item will shy away from it if you ask for the unbind price because of the potential for them to get easily scammed. it is a huge trust thing, but for the most part players asking for an unbind are legit. But, if you are selling something and needing it unbound, then most players would highly prefer you unbinding it instead of the trust game. Most big merchants do not have this issue, so it is more of a thing that happens with more "casual" player who cannot afford the unbind but want to sell something valuable.
Cheers.