I think it depends on the marriage and whether there is some 'traditional' set up where the man is considered to be the one who controls these things.
During my marriage we had joint accounts and kept a tight reign on spending but I ran the financial side. That wasn't to say my husband and I didn't consider ourselves equal, it was more convenient as I was in town more often. If I needed to spend a lot of money we ran it past each other so there were no surprises. Later when I started working it went into 'my account' but I always considered it 'ours'.
The main issue with only one partner having access to financial information is that the other is putting his/her financial welfare in their hands. With an addict, that's problematical. Do you have an emergency fund? Is money being put aside for your retirement? Have you set joint goals like a deposit for a house, or a trip or whatever?
Your AH may not want you to know the extend or type of his spending.