In most of Europe, the national government mandates a consistent set of road signs for the motorist. France may have 800 different cheeses, but Paris mandates a uniform system of highway signs. Wherever you are, you can find your way to the next town by following the signs. Yet Europe does a rather better job than we do at protecting and preserving local cultural distinctiveness. In America, by contrast, the only consistent road signs are those on the interstate highway system, which are mandated by our national government.
Local signs are a patchwork mess.
They are a jumble of sizes, shapes, and criteria. Sometimes street corners have signs, sometimes not. Sometimes they bother to direct you to major arteries, often not. If you're downtown looking for, say, Storrow Drive, good luck. Today he's driving in circles looking for Interstate 93 south.