Why so many Machine Learning Implementations Fail?

A recent article in Techcrunch describes Twitter and Facebook issues: algorithms unable to detect fake news or hate speech. I wrote about how machine learning could be improved, and what can make implementations under-perform - or not perform at all. And a colleague shared with me an article about how Facebook really sucks at machine learning. You would think that machine learning simply does not work, at least not as advertised. Here, I actually claim that this is not the case, further explaining what the issues might be, and in short, that machine learning might not be the culprit. It seems that the issues appear in situations that are not critical - such as an ad badly targeted, a racist tweet that goes undetected, or a piece of fake news that goes viral.