The thing is, we have studies upon studies upon studies that show repeatedly and undoubtedly that witness testimony is shit. If you show 10 people an event and ask them to describe what they saw an hour later, they will describe it in 10 different ways, frequently changing facts, adding things that never happened, or omitting important details. In trials, you get witness testimony from years before, and it's treated as if every single word said is absolute objective truth - like, we have the science to prove that no, actually, most likely it isn't, and it should be treated as "maybe true" at best.
Like so many things, I think the mistake here is to assume you can educate your way out of this. You could send every citizen through a six-week course on the problems with eye-witness testimony and some percentage of them will come out on the other side of that training insisting that, nah, if somebody says they saw the crime, then they saw it. We're talking about deep psychological biases carefully shaped by hundreds of thousands of years of evolution.
An eyewitness will tell the DA that they don't remember shit about what happened years ago, and the DA will reassure them that they police have ways of making them remember.
Source: A close friend of mine is getting pulled in to testify in a criminal case about some junkie that they may have called the police on three years ago. He has called the police so many times, and has dealt with so many sketchy, drug-influenced people, he can't even remember what the person in question did.