For example Andrew Carnegie(the robber baron of the steel industry), he was instrumental in starting the 72 hour work week, paying out less than fair wages and having dangerous working conditions.
The robber barons were known for their business tactics that would enable them to amass a wealth by monopolies. They would corner the market on a product or service and make it almost impossible to get, accept through them. To what extent was it justified to characterize the industrial leaders of the late 19th century as either "robber barons" or "captains of industry?"