If you do the substitution as you suggest and then add a unit test, then you have something ;-) Something on the lines of "describe countries with sales tax dependent upon the days of the week => Kerplakistan doesn't have sales tax on Mondays" So now it's self documented and self testing.

But I agree with your statement that there should be a pointer to the business rules somewhere. Otherwise it's difficult to have a meeting with the business side and ask, "Has anything here changed?" I think that's the biggest thing people miss out -- It's not that hard to find the thing in the code if things change. It's super hard to make sure you are on top of all the business requirement changes.