A perfectly free market would transfer power from voters to the oligarchs that would run the show. The US would lose its democracy and would look more like the mafia state of Russia. You'd have a plutocracy rather than a democracy. Precisely because the US economy is largely "free" or weakly regulated in that sense, compared to social democracies, the US is headed towards that plutocratic state, so the wealthy do indeed have some power over the US government. Libertarianism would exacerbate that trend, not remedy it.