I'm not arguing that US is universally free-market today, rather that it was less free-market 50 years ago.
A free market is a very specific definition, there are things like atomicity of actors and whatnot. Loads of regulations can help meet that, for example:
-Governments handing out tax credits to new companies helps free markets
-Governments setting in anti-trust laws helps free markets
-Governments setting disclosure regulations helps free markets
Some regulations harm free markets (namely things like entry controls), but others protect it. We need to learn to make the distinction