How can we improve the judicial system that monitors our politicians deals (spotting for fraud, corruption) when it is not in the interest of anybody involved?

Everything starts with you engaging in local politics.

You get the politicians your deserve.

If you don't engage in the local part of the political party that is closest to your views, then someone else will. That "someone else" might not have the same good intentions like you do.

The politicians elected in the lower parts of the political pyramid are the ones that will eventually rise to the next level.

So the corrupt ones in the top could have had a much harder journey if people stop focusing on the top and change focus to their own surroundings.