David Rolfe Graeber (/ˈɡreɪbər/; February 12, 1961 – September 2, 2020) was an American anthropologist and anarchist activist. His influential work in economic anthropology, particularly his books Debt: The First 5,000 Years (2011), Bullshit Jobs (2018), and The Dawn of Everything (2021), and his leading role in the Occupy movement, earned him recognition as one of the foremost anthropologists and left-wing thinkers of his time.
This is less an example of how anarchism can't do this or that, but rather that you can't have your insular little utopia if you're surrounded by powerful entities whose interests directly oppose yours. There is no right life within the wrong one.
I still don't see why a sewage system is cathegorically out of the question when the problems here are less "you can't organise the construction of a sewage system" and more "we still live in a globalised system which is fundamentally based on competition."
Did you miss the quoted bit where they talk about how they lack the of resources and expertise are a common problem? That’s the problem anarchists face IRL. The people that have these skills are incentivized to leave anarchist societies for ones that compensate them fir these skills.