I'm surprised Nintendo doesn't sensor. They wouldn't want to damage their family brand they've work so hard to create. I guess they really want the 3rd parties on board.
No, the difference is, that Nintendo is relying on it's age restriction system, which is far more developed than the one on the PS4. Switch got a certification as first gaming console for fully implemented age restriction system from the german rating board. And they are quite strict on that. But if you are effectively can restrict games to be used for children, you can be much looser about what is OK in games for adults.