With respect to the post office scandal, the issue is partly that the rules of the court mandate that a computer should be trusted unless there is a reason to distrust it, and partly because Fujitsu, The Post Office Ltd and their lawyers engaged in a criminal conspiracy to conceal and destroy any evidence that the computer system was highly suspect, to charge individuals with theft and false accounting when they reasonably believed them to be not guilty of the charges, and to prevent any defence lawyer from discovering how many other people were being charged with false accounting and theft by the Post Office.
I mean, to be fair to the court rule, it's terrible but it's not the main reason for the scandal. The main reason is conduct which could be described highly unethical at best, knowingly criminal at worst. I would like to see the innocent vindicated and changes to the system that allowed it to happen. Justice for the perpetrators is probably beyond hope, but there will always be some people to carry the can.