She also keeps her shoulders and swing level to the ground. That's also common. You hear coaches say 'Don't drop your shoulder' and 'Swing level.'
But at the point of contact, the shoulders are going to be tilted, and the hands are going to be higher than the barrel of the bat.
(Something ironic about this photo is that I was going to say that I really don't like for hitters to have a closed front foot during the swing, like your DD's. I think it restricts hip rotation and puts a lot of strain on the knee. But this here hitter keeps it closed and had a good career. I still don't like it.)
But notice the shoulder, bat, arm angles.
This is the #1 difference I see between softball and baseball swings. There is a point in the swing; at contact, where the knees appear to "pinch" together as an energy transfer. This can't happen effectively if they are too vertical.