Well, I think there should be laws against endangering people period, regardless of your activity. I don't know that sex has to be included in it. You may be endangering other drivers if you pull over on a freeway whether you're having sex or not. You could be bird watching. Frankly, I'd much rather the couple pull over than do it while driving. Do they have a specific law against that? Now, doing it upside down on power lines, in the middle of a rainstorm. Okay, I wouldn't oppose a law against that.

For instance, pulling over to the side of the road on the freeway. Many states prohibit such acts.