I don't think this is a case of knowing Cobol. I think it's a case of company's hiring the experts who were let go. Person A has X years experience with company

I don't think this is a case of knowing Cobol. I think it's a case of company's hiring the experts who were let go. Person A has X years experience with company Y. Person is let go. Mission critical infrastructure starts to fail. Person A is now a contractor with X years experience on that exact system. Sure they can hire a new guy for cheaper, however that appears to be what led up to A being let go. They suddenly need experience and A is willing at a much higher rate.