I am well aware that railroads still clean up their own derailments. What I was referring to derailments which are in-between being considered as minor and a major derailment. That is what mainly, I saw the road cranes being used for, while the wreck trains were called in for the large derailments. CSX and every other Class 1 which still had road cranes pre-PSR. Once the bean counters got involved, the maintenance costs got viewed as unneeded overhead. Which yes, on paper it saves money. However, the cost savings are quickly tossed out the window when you have to write a six figure check for Corman to clean up a derailment, which would have just been fuel and wages, had the road cranes been available. Plus the road cranes typically only involve an operator, plus 1-2 rigging guys. Whereas a callout to Corman, you are talking a minimum of one machine, two tractor trailers, multiple pick ups and 6-8 guys. And that's on top of the MOW guys who are on the site anyway to fix the track once the derailment is cleared. CN still handles most of their minor and midlevel derailments, because they have realized that they aren't saving money by using contractors for those.
Cost cutting which works on a spreadsheet, isn't just limited to derailment clean ups. Go back and watch mow personnel testify to congress and other government agencies over the last year, regarding the cuts to preventative maintenance. It saves money in the short term, but long term it costs more when something goes wrong.
To address your final point, as part of that, it was always my understanding that Pan Am didn't use contractors, because they didn't want to pay the premium rates they charged. Which when you have a major derailment blocking a busy main line, having a contractor work 24/7 on the clean up until the line is open makes sense. But I can see if there was a derailment on a main which sees 6-10 trains a week, I can see where it would make sense to them to clean it up inhouse depending on the size of the derailment.