Saturday’s state elections in South Australia and Tasmania were a study in contrasts: one a landslide and one a cliffhanger; a drubbing for Labor and an unexpected morale-booster.

In Tasmania, the Liberals secured a decisive majority of as many as 15 out of 25 seats, in the context of an electoral system faulted by its critics as a recipe for minority government and parliamentary gridlock. In South Australia, the single-member electoral system that privileges major parties will more likely than not find independents holding the balance of power.

Barring late-count miracles, the South Australian Liberals look certain to fall short in the lower house of 47, having most likely gained three seats from Labor and one from an independent off a starting point of 18.

Labor has an outside chance of making it to the magic 24 if late counting favours it in Mitchell, but the more likely result is that it will emerge best placed to offer the two independents a workable minority government arrangement by securing 23 seats to the Liberals’ 22.

The Liberals would thus emerge from a second successive election in opposition despite winning a majority of the two-party vote, in this case by a comfortable margin of roughly 52.5-47.5.

It’s made particularly poignant by the provision in the state’s constitution — inserted after the 1989 election, at which Labor was similarly successful in retaining government from 48.1% — which enshrines the principle of “electoral fairness” when electoral boundaries are redrawn after each election. However, the directive that boundaries should deliver majorities to the more strongly supported party unavoidably includes the qualification that this should only apply “as far as practicable”.

Little effort was made to give effect to this at the most recent redistribution, as it was determined that the wildly uneven pattern of swings in 2010 was unlikely to represent a long-term shift in underlying patterns of support.

Even if the redistribution had tortured the electoral map to strong-arm more seats to the Liberal side of the pendulum, there is no guarantee it would have achieved the desired result.

Conceiving of electoral fairness in two-party terms requires that independent-held seats be classified as belonging to one major party or the other — and given the normal orientation of Geoff Brock’s seat of Frome and Bob Such’s seat of Fisher, the election has indeed returned a “conservative” majority, if only barely.

Furthermore, Labor in fact picked up swings in about the same number of seats as the Liberals, important marginal seats among them. There can thus be no guarantee that Labor would have improved its position on a hypothetical alternative set of boundaries.

“The party in SA has good cause to plead the virtues of optional preferential voting …”

The fundamental reason the single-member electorate system is in the habit of favouring Labor in South Australia is that conservative votes are wasted in extremely safe rural seats, leaving larger numbers of city marginals leaning modestly to Labor. This has activated an interest among Liberals in electoral reform, in terms which are predictably selective and tailored to its present difficulty.

The party in SA has good cause to plead the virtues of optional preferential voting, which would reduce the flow of Greens preferences to Labor and convert its primary vote leads into victories with greater frequency. The traditional downside to the conservatives of this arrangement — that it endangers them in three-cornered contests with the Nationals — is of little consequence in a state where the Nationals only run candidates in a handful of very safe rural seats.

Another idea being floated — an indeterminate number of “top-up” seats being added to the parliamentary total to ensure a majority for the party with the greatest share of the vote — is considerably cruder and harder to justify.

Labor supporters with long memories may be contemplating with some amusement Liberal complaints about an electoral “gerrymander”, given how long it suffered under the real thing prior to the electoral reforms of the 1970s.

It’s interesting to note that nobody is contemplating a return to rural vote weighting, which would now perversely deliver fairer results.

Other possible solutions to SA’s democratic deficit are more elegant, but too radical to have much chance of being seriously entertained. One would be to follow Tasmania’s lead and introduce proportional representation, with seats neatly and rationally allocated according to shares of the aggregate vote. However, as was made clear by the experience of federal Labor’s second term in office, Australia’s political culture is allergic to the coalition-building and consensus style of politics that this would entail.

Another solution is to follow the American example and properly separate the executive and legislative branches of government. That way the office of premier could be elected separately from the parliament in a single statewide election, in which one vote really would have one value.

Meanwhile in Tasmania, and not for the first time, the result illustrates how the electoral system can influence vote choice.