If these so called underpaid contractors skilled enough they can definitely look for another job or try to get hired directly in Google or other companies. - Nobody has forced them to slave at contracting positions. - Contracting positions definitely pays better than flipping burgers - It's about supply and demand - If they have skills in demand they will get paid well.

I am sure you also outsource some aspect of your life as it's either not your core skills or expertise, similarly nothing wrong if these big tech outsource non core business aspect to contractors. In capitalist society it's government's job to set rules so that underclass employees are not exploited. Not corporations.