Spending caps, tax caps, and deficit caps are meaningless vote getting PR bullsh!t.
They are supposedly a "line in the sand", They are sold to the stupid voters as a limit Taxes, spending, deficit, what ever will not go above X level THAT'S THE LAW !
Politicians with nothing else to their credit can get a good number of votes by bragging how they introduced, sponsored, or supported the "cap".
As BM points out, when a "Cap" gets in the way of spending your money the same sanctimonious bastards simply vote to change the law and raise the cap higher.
IT'S THE LAW ! And it doesn't mean crap.