There are libraries that are giving out family cards now, so that among other things parents can keep track of what their children are reading, watching, or listening to, or as might be helpful in this case so that a person might pick up material for a spouse. But if a person applies for a card under their own name there is a presumption of privacy involved with that.
It takes just a little imagination and stepping out of the bounds of our own happy marriages to realize that not everybody has a loving a trusting partner.
This is off-topic but this discussion reminded me of it. Back when I was in my 20s and living with my parents still (I know, I know... trying to save my money ;-P ), I had started investing some money in a mutual fund. My parents had a mutual fund with the same company. At some point, I guess to save mailing costs, this company started sending all account statements to the same address together in the same envelope. So both my parents' statements and mine came together, even though they were completely separate accounts started by different people (not spouses) at different times.
Now, I had nothing to hide but still I was incensed. What gave them the right to consolidate our separate, private accounts into the same envelope? Well, I called and complained and they stopped doing that but I was shocked by it! Just because people live in the same household does not mean they want all of their separate bank, credit card, mutual fund statements consolidated into one envelope! Whatever happened to privacy?