I would agree with you ID, to me a collar is symbolic of commitment to each other and commitment to whatever that relationship may be.
In the same way that I have learnt to never try and understand how other people's marriages work, I have given up trying to understand how other people's bdsm relationships work, we are all so different.
He whom I choose to serve has not given me a collar since I have not yet agreed to marry him. His logic, which I agree with, is that since I still have a reservation about making the commitment of marrying him, I cannot be fully committed to the relationship, and therefore I am not in a position to accept his collar.
At the other end of the spectrum, I have respect for online collars if it is an established relationship and both parties are as fully committed to each other as their circumstances permit.
I would disagree with one point however - to me a collar shows that both Dom/me and sub are in a committed relationship, even though it is only the sub who wears it.
cariad