I get your entire point, except how giving/leaving trust sounds more like the adding to the trust list? I think all people who say giving/leaving trust mean feedback, never came across the other one.
Edit: may be like this:
Giving trust to X -> I trust X -> by adding him to my trust list?
Leaving trust to X -> Can't appear to mean anything other than leaving him a feedback..
I will try using feedback instead of trust. I knew trust wasn't the correct term to use, but I got stuck to it and didn't have any problems with that yet, so I just kept using it, just like I don't care about the grammar most of the times.
Edit: If you ask me, newbies are like to use 'trust' than 'feedback'. Feedback can mean a lot of different things too. The link text reads Trust too, so it isn't really surprising that everyone new is like to use 'trust'.