>>You'd think evidence of corruption would be relevant and worthy of mass coverage, no matter who committed it or how it was obtained.

Our justice system cares a lot about how evidence used in a trial was obtained. If it was obtained illegally, it is often thrown out.

There is a good reason for this. I'm sure you can figure it out if you think about it. Here is a good start for some reading: https://en.wikipedia.org/wiki/Exclusionary_rule