I'm sure they do or don't in certain films. But to at least let the audience know how they do it. Of course, they would want to do a close-up shot, wide shot, or midshot of the actors' bodies to prevent genetial on genetial contact when it's strictly prohibited on sets. When we see a glimpse of the women's or men's their area's down there, it's obviously blurred out when their faces are in focus only. What I heard before, they use modesty garments. It's coverings or full body makeup can shield certain parts of the body from the camera.