It is both the transmission and distribution networks.
The transmission networks are the highways of the electricity grid to move large amounts of energy large distances…between the generators and the consumers. The east coast grid is also interlinked to allow flow from low demand areas (where there is excess generation or supply) to high demand areas (where there is insufficient generation or supply to meet the local demand).
Traditionally generators have been near the energy source or on main routes for its transportation (e.g. large coal generators in the Hunter Valley next to coal mines or Gladstone Power Station on the train route between the mines and port). Generators also have been traditionally located away from population centres as they are seen as inconsistent with residential/urban land uses.
Renewables typically are less constrained in relation to location (can be close to urban centres through to more remote locations where there is less land use conflict or competition). In many locations where renewables are proposed there is either insufficient free capacity on the existing transmission line network (meaning that additional generation could overload the regional network) or in locations where there is no transmission network and the local low capacity distribution network is relied upon for transmitting the electrical energy (possibly ineffectively as it is not what it is designed to do).
The costs for a renewable generator to plug into a transmission network can be significant, $100s millions as transformation to high voltage is required and also switching equipment (namely a HV substation). Add in power line between the generators and the substation, the costs mount up very quickly).
When it is often said that renewables are cheaper than traditional generation types, this does not include the connection costs for the renewables to the main grid. These costs can make be a multiplier of the costs of renewable generation, especially where the renewable generation is lower capacity than traditional sources which is very iften the case. The network connection component of the total renewable costs to deliver it to the consumer can make the costs quite expensive. These costs are flattened out by spreading the network costs across the whole of the network and over all consumers.
When working in the industry, during early feasibility states with renewable generators, it was often discussed to reduce network costs to both the generator and to consumers that any new generation (new or traditional technologies) be located a close as practicable to existing HV substations, to minimise the whole of network costs.
While this is possible for say solar (e.g. solar farm near the substation built for Collinsville powers station, often wind is located some distance from the existing network resulting in high connection costs (impacting on consumer network charges).
There are also many other renewable generators which ignore the advice of the regulator (AER), network operator (AEMO) or the transmission/distribution companies and locate their facilities based on their own business decisions which may not be best placed in relation to the existing and future network configuration to minimise network costs.
It is possible that some of businesses which are crying foul may be those who invest large sums of money ignoring the advice of the industry, and then finding that the location they have chosen for their generators is not optimum from a network point of view. Such could have been avoided by consulting with the industry in the feasibility stages and also making decisions that benefit the consumer by minimising overall network costs (which are passed down to the consumer through network charges).
While the government can solve the problems, it may come at considerable costs. It would have been easier for the companies proposing a new generation to plan for an optimised connection rather than hoping the local network has the capacity an ability to provide a cost effective solution at the late stages of a projects development.
I have a cynical view as well 
