That's funny, I had the exact same thought in the US - so many road signs, so much to read. It was quite overwhelming. I think it may come down to familiarity: as you get familiar with the signage of a particular country they blend into the background (and you, presumably, just take in what they're saying subconsciously). By the end of the US trip I was much less overwhelmed by the amount of text on and around the roads.