I have seen it. But I have never reported anybody. I may have mentioned it in the local supply house ( rumor mill )
I have turned down lots of " side " work because I don't want the liability.
Often times around here it is a general contractor having one of his guys that "knows how" to do electrical doing some wiring on a remodel they are working on. Sometimes its a decent job.
If I am on a job and I see some not so bueno stuff that I have to fix because its my A$$ if I touch it. I will let the principal know the 2 options.
I can do I right and my company assumes liability or I can leave and he can get it cobbled and run that risk, either way.
Lots of people don't think about the consequences of hiring some electrik guy to something on the cheap. Once you explain the risk, safety, ins liability factors most of them want it done right. The ones that don't.........You didn't want their business anyway.