(Disclaimer: I haven't been to Ireland, but I do live closeby in the UK).
I find this interesting, because I found exactly the same thing true when I first went to San Francisco! It took me months to understand where to look for street signs (and I'm still fairly sure many junctions are missing them). I'm not sure if there's some pattern, but they often seemed arbitrarily placed... looking back, I also wonder if they're positioned more for drivers, whereas street signs here could be seen as more for pedestrians (whether this is true, or which is correct, is a topic for discussion).
In any case, I feel the author could expand their article by trying to think like a foreigner driving in their own country, and how that may also seem wrong! I personally think that this is perhaps a case of 'everyone has the wrong design', held together only by learnt habits.