You learn how to put those signs into context during your driving lessons, and fail your test if you don't apply that correctly.
I apologize if I gave the impression that I did not understand how to put them into context. Although I don't think my driving lessons ever mentioned it.
This is idle XKCD-style musing.
My driving test was so thorough that I had to parallel park between two entirely fictional cars. There was certainly no consideration of eccentric signage.