Daddy has access to all of mouse at all times and maybe more than he'd like (some of the time). Daddy decides what clothing mouse can wear or not. He decides what mouse does during the day. He controls mouse the way she needs to be controlled. If things go haywire, he'll decide what to do.
Additionally to all that, Daddy has all mouse's passwords. But in an odd twist mouse was reminded that she has access to everything Daddy too. All his passwords, work, financial stuffs. Everything! Should something happen to him, mouse knows exactly what to do, who to call and what is required.
Now mouse cannot advocate just handing over everything to a Dom just because he says he's a Dom or behaves like one. They cannot demand that you simply trust them and get nothing in return but a "good girl," after handing over the information. They must prove that they are worthy of such trust. The reality is that mouse has known Daddy forever, more than half her life. So ya, mouse trusts him.
The problem is that there are a lot of Dom types out there that just don't have their subs best interest at heart; they make demands -- in part because it's what they do and for some reason expect blind trust. This is something that causes mouse a little distress for some new submissive just embarking on their journey. What is too much? Certainly, some Doms would never dream of asking for such sensitive information but as mouse has read and time again other's have. Some have been devastated and financially decimated by their Dom's actions too.
Ultimately, each has to decide how much access is too much, but mouse asks that if you're new to this lifestyle, don't follow blindly or decide because you read on other blogs that others have done this. Take into consideration how established their relationship is.