alt Hacker NewsPeer review definitely does catch errors when performed by qualified individuals. I've personally flagged papers for major revisions or rejection as a result of errors in approach or misrepresentation of source material. I have peers who say they have done similar.
I'm not sure why you think this isn't the case?
Poor wording on my part.
I should have said "Peer review doesn't catch _all_ errors" or perhaps "Peer review doesn't eliminate errors".
In other words, being "peer reviewed" is nowhere close to "error free," and if (as is often the case) the rate of errors is significantly greater than the rate at which errors are caught, peer review may not even significantly improve the quality.
https://pmc.ncbi.nlm.nih.gov/articles/PMC1182327/