Each side does get to show opening remarks before presenting the bulk of evidence. And, each side can cross examine witnesses which create much more of a back and forth than you might think.
IMO, the real bias is expert witnesses get preselected and paid, so they tend to favor a specific side. This has allowed a lot of pseudoscience to be shown a trial and enter the literature. Forensic science is rarely validated because that’s just not its job.
Consider, two people that compare hair samples, but one always supports the prosecutors case. Now, which one do you think gets more work? When someone says something is inconclusive that's it they not going to get paid to show up at the trial just there initial 'investigation'.