There is not a single fair, well regulated economy in the world. Private interests of those with large amounts of capital skew the markets to their favor.
Who is "we" here? Because the current system is ran by people who have a vested interest in keeping things the same.
Also, I disagree on my comment being a fallacy. I'd almost argue the comment I replied to is a fallacy because it's comparing a theoretical well regulated market to the reality of what we actually have.
It's clear to me that such a thing could never truly work because it would require near omnipotence by whomever the regulating body is in order to prevent actors gaming the market.
I like markets, and would laugh if anyone went ahead and tried to make a purely capitalistic economy. Fair, well regulated economies, work.