In control over all finances

Let's say you were a stay at home mother and your husband was the one working. Would it be okay for you to control all the money and your husband have no idea how much money y'all had or how much money was spent? The reason I'm asking is my SIL said that she controlled the money and her husband had no idea how much money they had or how much money they spent. She even said he had no idea how much she had spent on Christmas. Do you think this is okay? Personally this doesn't work for me and my husband but I guess in her relationship it works because her husband doesn't seem to mind.