Because it's an unsubtle polemic that misses its target. All government inefficient? Check. And wrong. Charity as the single solution to collective action problems? Check. And has substantial real-world limits due to the free-rider problem. Medicare inefficient? Check. And ludicrously wrong.
Dropping a standard-issue screed into a thread tends to attract downvotes because it isn't serious.
At a completely different scale to those mentioned by others, council housing maintenance by Darlington Borough Council in England. I used to work for them and looked at privatising it; it was too damned cheap to be undercut by any of the private companies.
Government is full of bits that work very well, as well as bits that work very badly. Governments are complicated; sweeping statements are usually wrong.
https://news.ycombinator.com/newsguidelines.html