If you’re sitting in a bar with a half-dozen friends, and your liberal friend tells you that you have to pick up the tab because you earn more, your liberal friend is being authoritarian.
Suppose that liberal friend is your employee in addition to being your friend, and the reason he can’t afford to pay for his own beer is because you barely pay him enough to cover rent and food for his children. Yourself, you are quite wealthy, and could absolutely afford to pay him more, but there’s no one compelling you to, so you pay him as little as possible.
Aren’t you, in effect, limiting his freedom by paying him such a low wage? If all the competing jobs pay equally as poorly — if he can’t quit and find a better job elsewhere, in other words, and he has no choice but to work for you or starve, for whatever meager wages you’re willing to pay — then couldn’t you be considered a type of authoritarian in that situation?
Libertarianism is rooted in individual autonomy. The second you switch over to forced collectivism, you no longer have anything libertarian.
Unless they are full-blown anarchists, most libertarians will agree that there are times when it’s okay to restrict individual freedoms for the collective good.
We don’t allow people the individual freedom to commit murder, for example.