Its not about how obvious you think it is, its about how hard it seems to the user. And the harder you make it the fewer users you'll have.
Secondarily, you put your instructions in printed form next to the screen -- when all the user cares about is the screen itself.
http://dirtsimple.org/2009/05/how-we-get-stuck.html
TL;DR: The author's SO got stuck trying to assemble a kitchen cabinet, and couldn't figure it out. The author looked at the problem, checked with the manual, discovered the solution immediately, and got called smart. The SO didn't even bother. And the author realizes that if their positions were swapped, he wouldn't bother either.
There's something wrong with the whole class of people - that mostly seems to coincide with the "non-tech" group, though maybe it's more about problem-solvers/not problem-solvers. What's wrong is that they get stuck on the first obstacle and give up. Instead of assuming that there must be a simple solution and searching for it, they assume it's broken and quit.
Also, related, the famous XKCD chart: https://xkcd.com/627/.
To be fair, compiler messages can be needlessly cryptic, but if you copy and paste the error into Google you'll almost always find someone who did the exact same thing and had it answered quickly.
Also: “In fact, users don't read anything.”
http://www.joelonsoftware.com/uibook/chapters/fog0000000062....
when I showed it in public in an event, I saw the same loop many, many times:
1> user press buttons confused, see I am standing nearby, ask me what they do. 2> I do nothing if they have a SO near. 3> SO points user, that there are descriptions of the button right there in front of them. 4> User slaps his forehead.
In case there was no SO near, then I would point it myself, the reaction of people was still the same...
I concluded that ins't just that people don't follow instructions, is that they don't even try.