This explanation for the backwards-spelt “AMBULANCE” has caused the scales to fall from my eyes. Until I thought to see what I might be able to read in my rearview, I had no idea what that garishly painted boxy vehicle with siren ascreaming and lights aflashing might possibly be!
Of course, in light of the growing numbers of non-native English speakers, I propose that ambulances carry either billboards or scrolling displays on their grilles spelling their name backwards in various tongues. Maybe a little icon of an ambulance in reverse for those illiterate drivers out there. They also had better drive more slowly to give folks time to read in their mirrors. And cut with those distracting sirens - I can’t concentrate on reading with such background noise.
Yeah, this has been annoying me for years as well. Are there really drivers so incredibly dense that when they see a honking, blinking van speeding through rush-hour traffic they look into their rearview mirror and think “Oh, no worries, it’s only an ecnalubma. No need to get out of the way”?
Is this your first post on the Internet? Otherwise, how can you ask a question wondering about how some people can be “so incredibly dense”? 
Besides, how you ever looked at real drivers’ responses to sirens? Some move, some don’t, some think they are being chased and speed up, some get so flustered they try to move six ways at once, some wait to see what kind of vehicle it is, some are away from home and don’t recognize what the siren sounds like, and some have the radio turned up so loud they can’t hear a thing in the first place.
99.9% of the time, the things you think are too dumb to be believed came about in response to actual human behavior, which is 100% of the time too dumb to be believed.
And braille, they should have backwards braille.
In German: NEGAWNEKNARK!
krankenwagen? crankin’ wagon? are we talking about ambulences or ghetto suvs?
It comes down to pretty much the same thing in the end.
911 is a joke.