This is not true. The check engine light can come on in some cars if the gas cap is not screwed on tight enough - easily fixed yet treated as serious as a major engine malfunction.
In this day and age we can have something more informative than a check engine light. Tell me what's wrong, or at least have a "verbose" option I can enable that will let me see WTF it thinks the problem is.
I think the check engine light is a giant scam to get people to take their car in for service when there is nothing wrong with it.
As far as a verbose option, if you pull into an O'Reilly's or other auto parts store they will lend you, for free, an OBD-II scan tool with which you can read out the exact error plus any corresponding sensor data(freeze frame).
If your check engine light isn't flashing, it's actually because your vehicle has detected an issue with your emissions equipment that means that the engine control module is not able to regulate emissions to within EPA requirements. There are various reasons why this could be the case, but it usually indicates an imminent failure.
For example, mine is currently on because it's detecting a lean fuel condition in the cylinder bank when under high load, which means either that my fuel injection system is not able to keep up or that my throttle is letting too much air into the intake manifold. My car is still drive-able, but I definitely need to have it looked at because my fuel pump or injectors could be going out or my throttle could be faulty.
The point is that it's not a scam, it's providing you useful, predictive information. You just need to know how to retrieve it.
So, for a trivial cost you can get your verbose option. Most people are not going to have any knowledge or desire to have this information, so it's a silly feature to include.
You will need an Android phone already, but these days that is pretty common (particularly for technical people). Just get the error code and Google it, it becomes pretty obvious what it is.
I know my 2007 Lexus has those programmable options like beep durations and such, but I have only found two solutions - paying the dealership $60 to change them, or buying a $15 android app that changes them. I could do it myself, but the codes (Lexus Personalized Settings) are secret. Did you find a free alternative to modify your Prius settings?
http://priuschat.com/threads/geniii-prius-custom-pids-for-to...
But the short is someone else has done the hard work so you don't have to.
Pro tip: As the others stated, they make good obd-2 readers for cheap and you can also go to many auto parts stores and they'll use theirs to give you the code print out for free.
The point that I was trying to address is that if there is a critical warning that you can't do anything about, there's no more info needed than 'stop and seek help' which is perfectly served by a simple light. Or do you want a 1 page problem statement to flash up on the dash and explain why you really need to pull over. The only reason you would do such a thing is if you wanted the user to make the evaluation of whether or not it is important or something that can be ignored.