There are of course exceptions. And some individuals like to put on exhibitions for the rest of us whether we are interested or not. These are the individuals that create problems for the majority of nude beach users. It is these individuals that attract the attention of local officials. Local officials properly recognize that society in general does not want to be exposed to sexual acts.
Laws are on the books in all states that make such display illegal.
The difficulty arises when well meaning officials create new laws which are not sophisticated enough to properly identify what it is they are trying to eliminate. Under these conditions laws are created which prohibit simple nudity. Review the material put out by the religious right. A close reading suggest it is the details of sexual intimacy that they want to control or eliminate. Rather than be specific about private things which they really should have no interest or concern they have chosen to make mere nudity illegal.