A lot of these problems come from deference to experts who wear the hat of science. For instance, https://en.wikipedia.org/wiki/R_v_Adams a man was convicted because an expert said the DNA gave 1 in 200 million chance of incorrect match (or something similar), which is incorrect. I don't remember enough details to look it up, but I recall a US case where the prosecution repeatedly used an expert with a history of lying on stand and of course people wrongly spent time in jail for that.
I think a bigger issue here, at least in the US, is prosecutions seems to have a really easy time finding experts, often on the same payroll as the prosecution, who say the things needed to get a conviction and jurors are encouraged to blindly trust that.
That's the whole point of the adversarial system. The prosecution finds experts that state one opinion, the defense finds experts that say a contrary opinion, the juries pick out whose opinions they want to believe. That's the whole point of expert witnesses - they are the only witnesses in the courtroom who are there for their opinions.
The problem is that one side of this equation has a cottage industry of well-funded experts to pick from, but there isn't a cottage industry of well-funded 'bullshit debunkers' to work for the defense.
The Daubert standard says the judge is a gatekeeper who can rule that a given expert's opinion will not be presented to the jury unless the expert's opinions are relevant, reliable, and based in scientific knowledge.
It's more than that. The judge usually has a good relationship with the prosecution, and the judge is deciding on what the jury is allowed to see and what expert witnesses are allowed to testify as expert witnesses.
>the defense finds experts
defense finds nothing because it's a public lawyer and he barely can afford paper for photocopier, so no highly paid experts for you if you are poor
I think a bigger issue here, at least in the US, is prosecutions seems to have a really easy time finding experts, often on the same payroll as the prosecution, who say the things needed to get a conviction and jurors are encouraged to blindly trust that.