That seems to be painting vanilla partnerships with a pretty broad brush stroke.
For many D/s and M/s couples, what it is that we do is an expression of and a manifestation of the trust that we have as partners, the activities are not what gives birth to the trust. Yes, we do "trust" that our Doms and Masters keep us safe from physical harm when we play, and safe with others at a play party etc., but technically a vanilla partner does the same thing by simply not exposing his significant other to those "dangers."
You're right, there is a "level" of trust between a Master and a slave that isn't there between two vanilla partners - there is plenty that vanilla folks don't have to worry about in regards to each other, but that doesn't mean that level of trust is any better or deeper. It's simply a different level.
Maybe I am misinterpreting your comment, but I still think each couple will defer to the things that are most important to them.