Why is it that sellers who think it is OK for them to breach ebay policy by leaving feedback for non payers are often the ones that complain loudest about other members breaching policy by not paying etc?

The rules are there for everyone and the consequence of not paying can, and should be, a strike which helps protect all sellers. The consequence of leaving false positive feedback are the possibility of a policy violation reducing your TRS compliance,  the addition of a green dot for the buyer with no comment because that will be removed, the possible removal of the UPI strike and buyers not purchasing from you because it is obvious you don't care about following ebay policy.

Now tell me again why you think leaving a neg for a non payer is a good idea?