As others have said, you're unlikely to change her overall approach to spending so I suggest that you accept that this is her way, that it's not necessarily worse than yours, and find additional ways to save within this established framework.
With that in mind, how about suggesting she reduce her variable budget categories by a set amount, across the board? For example, if she currently has budgeted monthly $200 for restaurants, $100 entertainment, and $200 for gifts, suggest she pick a reasonable percentage to reduce each category, say 5-10%, and don't change anything else about the ways she spends money. A small percentage reduction in each category shouldn't be too limiting for her, she can continue to be able to spend through each category, all the while increasing her savings. Over time, once she's accustomed to the new normal of the lower budget amounts, she can reduce the categories even further.
With this kind of approach I think it is actually better to have a lot of budget categories because cutting down by a small amount in several areas is often mentally/emotionally easier for a lot of people than cutting down the same exact amount from one larger bucket category. Using the example above and assuming a 10% reduction, your wife could very well feel that spending $20 less on gifts and $10 less on entertainment and $20 less on restaurants is not to big of a change to her current spending habits, whereas $50 from a general $500 fun money fund might seem like a big sacrifice.