If you define Slavery (or Serfdom, in the von Hayek sense) as "Using the Law to force individuals into an involuntary exchange of goods and services" it becomes clear. In the contemporary sense, this is done by government, hence the term "Statist Neoslavery", as opposed to individuals being "owned" by other individuals. When government uses taxation to remove freedom from one individual, then awards it to another individual via a government program, it fits the definition.

I prefer wood to plastic, leather to nylon, waxed cotton to Gore-Tex, and split bamboo to graphite.