The Federal Rules of Evidence are based on the California Code of Evidence. The FRE Advisory Committee notes frequently reference analogous California sections and state court cases to guide interpretation of the Federal Rules. Before the federal courts used common law evidence rules that were difficult to apply uniformly.
Also, what about Court TV? I don’t watch it.
The rules of evidence were developed over several centuries and are based upon the rules from Anglo-American common law brought to the New World by early settlers.
Anyhow... glad my little "bs" post was enough to spur you to finish your scholarly half-thought-out post.
You are welcome.