: If free trade produces the greatest economic situation, why is it that free trade is never allowed to produce its end results?
Youve answered it already. If the 'greatest economic situation' were to come about via free trade then it requires by definition the near-absence of government and the absence of so called 'positive rights' such as 'free' health care which require the perversion free trade in order to realize.
Free trade requires that no one is being forced by others (ie, not by their environment, but specifically by other people using force to achieve their goals) and that no one is constrained by unchosen obligations placed upon them by others.
In other words if 'we' all wanted to establish health care facilities for every person then 'we' would have done so without the vast bureacracies and the IRS. Evidently 'we' did not all want to do this, and interest groups have used government to enforce their interest at the expense of all, whether they agree or not. This is true of every govt programme.
:Why is it, to protect free trade, one has to go against free trade and squash monopolies?
Wrong way of looking at it. Monopolies are mostly created by regulative intervention, eg govt standards, border taxes, discriminatory corporate welfare and the uneven application of the regulatory body of laws which govern companies. In other words govt can help stack the cards in one companies favor, and regularly does so at the expense of every one else. 'monopolies' that grow up by having superior (or at least more popular) product are 'monopolies' only as long as they remain the favored choice - hence they need to stay popular to stay on top.