There's also the difference between what a consulting company bills for the COBOL developer and what they pay the developer. Not every consultant is the captain of their own ship.

My first job after college was a software shop organized in a "services" model, where clients would have to sponsor teams to do feature dev or support beyond initial onboarding. It's been a long time and my memory is hazy, but as I recall I was expected to bill ~40 hours a week to clients and if I only worked 40 hours that week (being OT exempt, this was always the goal), my hourly pay came out to between 10-20% of what the company billed the client.

So $500/hr on the bill and $45/hr on the paycheck both manage to sound plausible, even at the same company.