This bothers me all the time. Several of the assumptions required to have a "free market" aren't met in the United States. If you try to have a conversation around that, you're a "communist", even though you're literally discussing how to have a free market.
Communism is basically orthogonal to the whole free market thing, though. Capitalism is defined as a system in which you can pay somebody a wage that's less than what you get from selling the products of their labour. Other than some basically technocratic stuff (how do you make sure workers are properly compensated) there's no specific communist problem with free markets I can think of. There's also no shortage of capitalist nations that were extremely anti free markets.
It's at least somewhat coincidence that communists have typically gone for high state involvement - Russia was, before it was communist, basically an entirely non-free market, and most industry happened at the behest of the Tsarist bureacracy, which was massive. So the USSR was big on state planning kind of as a continuation of that.
