I see nothing wrong in having a joint account with a spouse. Marriage is based on the foundation of trust. Both parties must have trust for themselves. 

Also, marriage should be open. There would always be security on the part of both the wife and the husband. Any little hint at a secret being kept could spell doom. 

I have seen couples practise this and they live happy. It's all about understanding. 

The wife loves her husband and understands that he wants the best for her. The same goes forever the husband. 

Insecurities in marriages are the reason why people cheat. If I, as a manufacturer knows that my wife is not a gold digger, there is no reason why I should hide my account details from her.

See, marriage is a union, two entities becoming one. Would I hide some things from myself? Certainly not! Then, I should not hide anything Whatsoever from my wife. 

The way I'm planning my marriage to be Islamic such that even if I'm being seduced or a lady makes a pass at me, my wife would know about it. I'll want for her to do likewise. This breeds trust in the home. 

If you know who you are married to, you would never hide anything from your spouse.