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.