The powers enumerated within section 51 are reflective in their topics of being those that Australia's colonies perceived as being best within the purview of a national government.
This is because these sections have been interpreted by the High Court as wide in scope, and so are extensively relied upon by the Commonwealth when attempting legislative enactment.
Following this case, the reserved powers doctrine was abandoned; although it has notably reappeared a number of times in argument by State governments when arguing against Commonwealth legislation.
In effect, the Commonwealth can make grants subject to States implementing particular policies in their fields of legislative responsibility.
However, since a uniform federal system of income tax was introduced in 1942 (under s51(ii)) a vertical fiscal imbalance has arisen and the Commonwealth Parliament has had a vastly larger budget.