What we're talking about is a much more specific phenomenon than "unregulated free market capitalism". In fact, in an unregulated market, there would be no regulatory arbitrage opportunities, by definition (e.g. Uber would have no reason to exist since taxis would already be unregulated).

The idea of the argument (or more accurately the joke) is that Uber is unregulated free market capitalism. It is what happens to the taxi market if they would lift all regulations. Uber’s whole “innovation” was to find a way to be unregulated while most of their competitors were still regulated.