You can't be serious. State sovereignty and state laws are built into the whole structure of our Free Constitutional Republic. Our Free Constitutional Republic has been one of the few exception is the recorded history of freedom and well-being for the average citizen - certainly not a "disaster".
The issue of differing state laws that you're concerned with is moderated by the Full Faith and Credit Clause in which one state's courts honor the judgments of courts in another.
it is a mess
Freedom and our Free Constitutional Republic can be slow and messy, but it's WAY ahead of whatever's in second place.
No, our constitutional rights were never meant to be different when crossing a state line. That is a federal issue. Whether speech, guns, search, whatever, these rights are not subject to state laws. Well, shouldn’t be. The courts haven’t fixed this, so the other branches of government must step in a fix.