The error, IMO, is thinking that anarchism is something that has to be implemented or practiced. Anarchists are not saying governments do not provide services. They are not saying that they know how to create a utopia. They are pointing out reality and irrational arguments. An atheist can acknowledge that religious people and institutions provide some good to the world, that doesn't mean they have to accept that religion as legitimate "truth." The anarchist merely points out that definitionally many of the institutions people defend (people called "Statists) are violent and aggressive and anarchists ASK whether it is possible to satisfy those same needs in a voluntary way and seeks to prove that it is possible. Statists assume it is not possible without serious inquiry. A non-anarchist simply accepts that because someone has power and renders a service that it is legitimate no matter how little choice is involved (e.g. referring to institutions that have a force-based monopoly as if you had any choice in choosing their services), how little experimentation and variety, how little technology, and no matter how horrifying, irrational, and lacking in evidentiary support their claims are.