Personally, I think that in an ideal world what you're suggesting should apply. I think the real world is incredibly complicated, and politics in fact is really deciding among a series of greys, not black and white.
I'll give you a very specific example. Obviously a portion of the municipal workforce, especially on the operational side, is unionized. That's just the way it is and has been—just as it is, in fact, at the federal government level. There are certainly cases in which collective bargaining agreements that have been negotiated with the municipal union have been negotiated with the understanding that some of their outsourced contracts are going to include closed tendering.
So hypothetically, if that were the case and you used it as a negotiating tactic to reduce the cost of your contract terms with the bargaining units of your operating unions, and the savings outweighed any potential increase in costs of your outsourced work, might that not be a trade-off that a politician sitting around a council table would have to take an interest in?