So shouldn't ALL the loops be unbundled?

An item on ZDNet caught my eye and made me think tangentially about the telecom Local Loop Unbundling (LLU) - basically it is talking about how the cable companies in the U.S. are currently facing similar unbundling threats from regulators over there and have a similar retort in terms of "we've made an investment, and I don't think the government should be coming and telling us how we can work that infrastructure, simple as that".

The query this suddenly raised in my mind was - why isn't the Government regulating for ALL the local loops to be unbundled?  If there is such an economic bar to investment in the local loop then surely this means that where additional loops have been created (EG by TelstraSaturn in Wellington) then all of these should be subject to the same unbundling legislation?  If fair and reasonable rental rates are to be enforced as suggested - and why Telecom's competitors are saying they shouldn't be complaining on a commercial basis - then surely those same competitors would not be disadvantaged by a compulsory rental arrangement on their own lines?

If not what REALLY is the difference? And please do not come whining about the lines never having been "sold" to Telecom - either they were and they should be theirs to charge / monopolize as they please, or they weren't and this could have been sorted out through a court case, not new legislation.
Tags: nz, new zealand, telecom, LLU, local loop unbundling, politics, legislation