Comment by elzbardico

The cynical me believes that there's not way kickbacks are not involved. A lot of times a third company acts as an intermediate on hiring those contractors, and their fees and markup easily make the same worker costs sometimes 2x their original salary.

The usual excuse for that is that labor is classified as OPEX, while hiring consulting companies can be classified as CAPEX, and the stock market likes when companies lower their labor costs to "invest" more.