Why is someone allowed to leave negative feedback after they have lost a case against you?

[raycarp.0646]

I had a situation where a buyer claimed they had not received an item and raised a case against me, claiming that they had received a damaged envelope. I send them video proof of the item being posted and they admitted that I was not at fault and lost their case ( the way the coin was enclosed in cardboard in the envelope meant it was impossible for accidental loss ).  They would not provide evidence for me to claim from Royal Mail and refused to claim themselves. 

They've been allowed to leave negative feedback for me but I can't now leave negative feedback for them to warn other sellers about the theft that took place.

[john1297576]

"not received an item"

I would say that the only reason you won the case was because the buyer opened the wrong case.  If they opened a Not Received case it makes no sense to then say they received an empty envelope. They received something.

The correct case should have been Not as described which you would have lost.

[raycarp.0646]

I agree with you. They said they received an empty envelope but would not send me a photo of what it looked like. The coin was so well packed it could not have fallen out, even if the envelope was badly torn, and so it was fraud or theft. I'd find it hard to understand that a postman would have put an empty and ripped in half envelope through the letterbox without explanation.
My question was around why Ebay allow negative feedback against me but do not allow me to post negative feedback against the buyer.

[1902elder]

It is not possible to leave anything other than positive for a buyer, this has been the case for many years. When it was possible it was often abused by sellers leaving buyers afraid to leave honest feedback even when justified. Don't be tempted to leave a negative under the positive dot, buyer can have it removed and it is a black mark on your acount.