You’re missing the point. Of course there are (enormous, life-ruining) mistakes, but that’s not it.

With software, generally the only people with the means to demonstrate the software is flawed are the people in control of the software and associated data.

Don't forget the hardware. The hardware is also inscrutable by people who are not a specialist in the field of that hardware.

I don't think demonstrating that DNA evidence against you lies is any easier.