Local courts may be primarily concerned about keeping the peace, which can translate into maintaining the local status quo. So they may convict recreationists of trespassing, or uphold river closures, restrictions, or abuses promulgated by various government agencies, regardless of navigability law and the Public Trust Doctrine. Another problem with going to court is that sheriffs, landowners, government agencies, and reporters tend to assume that if you are going to court, that must mean that at present you do not have the legal right in question. So going to court creates the wrong impression. Instead of going to court and thereby focusing attention on controversy about river law, you want to focus people's attention on the cases that have already been decided in your favor by the U.S. Supreme Court, and you want to emphasize that the local landowner or sheriff or government agency is violating those court decisions.
Courts usually have a backlog of urgent criminal and civil cases.
The District Attorney may suspect that river users have valid legal rights, but may feel that it is not worth dealing with. This costs the river users far less than it would to take the issue to court. But the net result is that they do pay a fine. In this way, a river closure or restriction can be enforced for many years even though it is unlawful. In sum, even though the law is on your side, going to court over an unlawful river situation is usually a poor use of your time and money.