I’m assuming Facebook is not so incompetent they can’t show an ad to its intended audience. I think the main issue is to do any sort of ML or user based targeti

I’m assuming Facebook is not so incompetent they can’t show an ad to its intended audience. I think the main issue is to do any sort of ML or user based targeting, you need to have a minimum amount of data to make good judgements in an auction. But then you realize you have multiple ads that are competing against each other and another ad might convert better or most important of all: pay more. Thus even if you have an ad which is targeted to that specific user, it might not get shown. Sometimes it is better to not show an ad at all. With all these trade offs, the result can sometimes look quite bizarre.