I noticed that in the US almost all signage uses text instead of symbols. For example, writing "No smoking" on a sign, where in Europe you would have a crossed-out cigarette.
I don't really understand why this is done, since well-made symbols are also understandable for illiterate people or those not speaking the language.
In Europe you have a lot of languages and nations mixed. People who design signs know and care about that. In US you have a huge country where everyone speaks the same language. People who design signs don't even know it's a problem that needs to be solved.
Explain to me the difference between these three signs: 1. a bicycle on a blue circle, 2. a bicycle on a white circle outlined in red, and 3. a bicycle on a blue square.
On the other hand having to read all that in text while you're riding by isn't very reasonable either. Complex signage is only as good as your knowledge of it, which maybe is why passing a driving test in Europe is so much harder; it requires knowledge we just get from being able to read in the US.
It was a comment for Americans who might not know the signs; not really an argument.
But really, if you're driving then you should have done a driving exam and test in your home country. Then you're ready to drive from Romania to Ireland (with the help of some tunnels and ferries) and be able to manage reading the road signs the whole way. This is possible because of a (mostly) shared iconography. Of course, on a bike you don't need to pass a test but you should do a little bit of studying to make sure you don't get a fine.
The US doesn't need this because it uses English.
This is also completely distinct from keyboards which aren't even QWERTY across Europe. There are also AZERTY (France) and QWERTZ (Germany) and some countries like Belgium have all three in the same office as people have different preferences. And pair programming is as painful as you can imagine.
I agree, some signs need to be learned, and traffic signs are a prime example of that. On the other hand, many signs with fewer fine distinctions can be made with pictograms that require no prior knowledge of conventions.
That being said, traffic signage is a mixture of both, where some meaning is given by convention (e.g., white background and red border means "not allowed"), and then extrapolated by pictograms (bicycles not allowed, trucks not allowed, pedestrians not allowed).
Edit: A certain cultural context is of course always required, to know for example that a crossed out cigarette applies to smoking in general and doesn't mean that you can smoke pipes, cigars, or bongs. Such 'misunderstandings' only happen with QA engineers though. ;)
blue circle: something you MUST do (in this case, indicates a path that can only be taken by bycicles)
white circle with red outline: something that is forbidden (the road is forbidden for bycicles)
the last one indicates a bycicle-only path crossing the road, 150 meters before it you should see a white triangle outlined in red ("danger") with a bycicle inside it
I don't really understand why this is done, since well-made symbols are also understandable for illiterate people or those not speaking the language.