Yes, usually one is better than the other. I am good with money, but my husband is far superior in his knowledge and analytical skills, and he does not mind doing it. Beyond fine with me for him to handle the financial duties.
In the case of my hapless sister and her husband, both are smart and either one would probably do the job, but I think it is a communication and power issue.
That is great that your son and his wife worked out their situation. One of my sons lets his wife handle all of the money issues. She does okay, and I am pretty sure they don’t have any credit card debt. IMO, she wastes an awful lot of money on dumb stuff, but it’s none of my business, so I keep my mouth shut.
“... it’s none of my business, so I keep my mouth shut”.
I had to laugh when I read that. As a “new” married couple, they dealt financially with her parents (mine are deceased). Now, usually people think that the father-in-law is more mature with money and wise about financial advice, right? Not in this case. The FIL told them they should buy a new car and actually questioned why some of their furniture was nice hand me downs. They both learned to ignore his promptings especially since HE wasn’t the one paying for it. LOL!