A minivan with tinted front windows is not OK, because pedestrians and other drivers at intersections can't see where the driver is looking. You don't need to be able to see the rear seats, which is why those can be opaque on a panel van.

I have no issues with rear windows being tinted or not. Sure, express yourself however you see fit. It's the front windows that should not be (but often are) tinted, and yet police will watch them drive by and not lift a finger.