The reason is that they specify a boolean value as either "true/false" or "yes/no".
The last alternative causes problems not only for the Norwegian country code (no), but also in cases where you need to specify the actual word "yes"
You could of course end up with the same problem if you need to specify the literal "true" and "false", but by overengineering the acceptable boolean values, they increase the potential problem areas.
A Boolean represents a true/false value. Booleans are formatted as English words (“true”/“false”, “yes”/“no” or “on”/“off”) for readability and may be abbreviated as a single character “y”/“n” or “Y”/“N”.
Regexp: y|Y|yes|Yes|YES|n|N|no|No|NO|true|True|TRUE|false|False|FALSE|on|On|ON|off|Off|OFF
I feel like the Makefile syntax has some pesky warts, like not breaking when there are spaces in filenames, requiring tabs[1], the ceremony around PHONY targets... If you take the legacy stuff out of make,
[1] Apparently it can be fixed with a complex .RECIPEPREFIX incantation which behaves differently in different versions of GNU make, and was conveniently added just one minor version after Apple has graciously decided to stop updating all their GNU software versions.
Redo, ninja and tup seems like trying to do that, with their own twists, but none of them really managed to nudge make out;
But if people have colons in filenames, for example for timestamps, all bets are off, and make chokes spectacularly.