I think that in some cultures or economic classes, in a time when the man was relied on for everything financial, and his wife wasn’t supposed to spend anything without his permission, it was common for a woman to keep her own account or money. It was the only thing she had to protect herself should she get divorced. These were times when women usually did not have their own incomes. It was also common in households where the man would fritter away the money on drink or horses or something. It was a way for the woman to get food for the kids.
Nowadays, women are more likely to have their own money because they have their own jobs. If the family shares the incomes, then it seems good to have one account. The reason for having a secret account is to have extra savings for emergencies or surprises. This, it seems to me, would be in cases where the woman (or man) doesn’t trust the thriftiness of their spouse, or things that the relationship is heading for splitsville.
In your case, @Frenchfry, it seems like your mother was giving you advice from an earlier generation that may or may not have relevance to you. Only you know your husband’s character. However, you are following a tradition that is not uncommon in older times, especially in working class households, where everyone was living close to the edge.
Guilt, I think, should not drive your decision. If you need safety, then the account is important. If you need to save money for Christmas gifts, and that money wouldn’t be there if you left it in the joint account, then you should keep the account, and keep it private. It all depends on the spending and saving habits of your husband.
My wife and I share all our accounts, as far as I know. There was a time when I was considering trying to set up my own account—when I was thinking I wanted a divorce and I wanted to save money for a car and a separate house. I never went so far as to set anything up, and now it doesn’t matter. In any case, I never would have wanted to cheat her out of anything, if we had gotten divorced.
I don’t know how separate accounts work. It seems a little ridiculous to have to calculate each person’s share of all the bills. One would have to hire a full time accountant just for that, I think. Maybe people divide it up into responsibility for the mortgage and the car and all the separate other bills and try to make it work out according to their contribution to the household. Although I think the each member of the couple always contributes fifty percent no matter what they do. Resources of the couple are not derived from outside jobs. They are derived from the relationship, of which each member is always exactly half of the couple.
Of course, not a lot of people see things this way. They see income generating work as more important than household work. The woman is the servant of the man and blah blah blah. Thus separate accounts (of a different sort from yours).