The root of all trust is eventually some human, or group of humans. See "Reflections on Trusting Trust." At least so far, Apple has convinced me that they are both willing and competent enough to maintain that trust.
Purchased music is DRM free. Streaming music was never DRM free, since you arguably do not "own" music that you have not purchased. Though I'm sure record labels would love if they could get DRM back on purchased music again.