I've wondered about that, having worked on the inside and looking at it from the outside. The answer is the amount of information that Parliament gets is “that big”, compared with “that big” within the department and “that big” in the Treasury Board, and so on all the way along.
I think Parliament could get more information, but the question is, can Parliament use it, and how would it use it? I don't see that there's a matter of confidence that you couldn't get more than is given, at current times, in the estimates.
Having said that, even the estimates you get now, with their meagre descriptions of programs and so on, is far better than 50 years ago—far, far better. Perhaps we could give a little push to get more in there.