Whether or not Microsoft can be trusted is not relevant. It's just very surprising to me that Microsoft itself blindly trusts disk vendors, instead of using their own encryption layer on top.
Ahh. I would guess that they aren't blindly trusting them. Given Microsoft's historical relationships with hardware vendors I would bet they have at least partially audited the firmware.
Yeah, I can imagine they'd conduct audits for firmware on the hardware they ship with their own products. I doubt they look at much beyond that though.