A couple thoughts:

Emphasis on collars: as has been discussed on many many threads- who does and doesn't have a collar (or has given one) is not much of an indicator of anything.

Who trusts: all the emphasis so far has been on the trust coming from the sub, and the dom/me simply being trustworthy. Personally, developing trust has been a HUGE process for me, developing domme. Trusting myself, trusting that I can do what I set out to do, trusting that this is not a game, trusting that my him is genuine... Its hard!

And, developing that trust is what led me to get him a collar.