In the UK the vast majority of prosecutions are made by the Crown Prosecution Service. The CPS are civil servants and, unlike in the US where they elect the guy emptying the trash, the crossing guards and the receptionist, these are just career lawyers.
You may remember Horizon not so long back, which was a gross misscarriage of justice in which large numbers of people who effectively worked for the Post Office were accused of crimes, in some cases jailed and even in a few cases committed suicide. Horizon is exceptional because, since mail was historically very important, the Post Office actually did have the same power as a Crown Prosecutor. Those cases were still sometimes really the fault of the CPS (not least because the CPS has a legal right to just seize control of, and then terminate a prosecution if they believe it would be prudent to do so) but are exceptional because most organisations could not have done this even if they wanted to try it.
Most importantly here, the CPS has a "Test" https://www.cps.gov.uk/publication/code-crown-prosecutors#se... to tell them whether they should prosecute people. This is going to weed out a whole lot of the worst examples you'll see in the US.
You may remember Horizon not so long back, which was a gross misscarriage of justice in which large numbers of people who effectively worked for the Post Office were accused of crimes, in some cases jailed and even in a few cases committed suicide. Horizon is exceptional because, since mail was historically very important, the Post Office actually did have the same power as a Crown Prosecutor. Those cases were still sometimes really the fault of the CPS (not least because the CPS has a legal right to just seize control of, and then terminate a prosecution if they believe it would be prudent to do so) but are exceptional because most organisations could not have done this even if they wanted to try it.