DP and I have a joint account where all earned money goes into and all household bills are paid out of.
We save jointly for annual expenses (car insurance, Christmas, holidays) and each get an equal amount of cash for free spends.
I check the balance on the joint account every few days to make sure there is enough for the direct debits and Aldi shopping and we don't generally touch it for other spends, using credit cards or our personal cash accounts (the amount we get as free spends is reduced by the amount of personal spends on the credit card in the previous month - credit card is paid off in full every month and earns cashback).
Joint accounts with full access are fine, providing that neither partner spends the mortgage money etc, because that leads to unnecessary bank charges and bad credit records.
Separate accounts are fine, providing both partners contribute fairly, based on their income.
I think the main problem is when one partner doesn't have free access to money or the amount of personal spends is unequal. However, the amount of free personal spends must be affordable, and based on what is left after bills including child related expenses have been paid, and savings have been made, at least for known annual expenses like car insurance, Christmas and holidays if you have one and some savings for things like car replacement, house maintenance or unspecified 'rainy days'.
I don't think its fair for anyone to expect to be able to spend hundreds per month on luxuries like clothes/eating out/work lunches/coffees/gadgets if the above mentioned basics have not been covered. This is where it is crucial for couples to be on the same page, for their financial relationship to be a fair and happy one.