> To be fair, though, in the US, the House also has unfortunate proportional-representation anomalies, too, because the total number of Representatives has not changed in over a century. See Wyoming vs. California for an illustrative example.

This is not unique to the US either. Section 24 of the Australian constitution guarantees each "Original State" [0] a minimum of five seats in the House of Representatives. On a population basis, Tasmania should only have 3 seats, but due to this clause they have 5 instead. This means Tasmania gets one seat per 114,240 electors, compared to one per 179,021 for NSW. This means Tasmania's seats-per-population in the House is 1.576 times that of NSW.

This is actually more disproportionate than the US House – Wyoming gets 1 Representative for 587,618 people, California gets 1 per 758,269 people – hence Wyoming's seats-per-population is only 1.290 times that of California. (Australian politicians have significantly fewer voters electing them, but that's almost inevitable with a population over 13 times smaller than the US – although consider Ireland, who have 174 seats in their lower house, but only 5.308 million people, meaning each TD only represents 30,000 people – that would be like Australia's House having 888 members, or the US House having over 11,000; if the US House had Australian-sized districts, it would have around 2000 members)

One difference is the size of the US House is at the discretion of Congress, so by increasing the size of the House, they could reduce the disproportionality. That is not possible in Australia without a constitutional amendment [1] since the Australian constitution requires the House to be "as nearly as practicable" twice the size of the Senate. Since the Senate has six states with 12 senators each, for 72 senators (plus 4 territory senators, but the High Court has ruled they don't count for this purpose), the House must be "as nearly as practicable" twice 72, which is 144 members. Currently the House has 151 members – but the 5 territory representatives don't count for this calculation, which brings us down to 146, which is "as nearly as practicable" to the required 144. The phrase "as nearly as practicable" lacks a precise definition, but it would seem any deviation big enough to significantly impact proportionality is likely to be ruled unconstitutional, while the small deviations (a handful of seats) that have thus far gone unchallenged are unlikely to make much of a difference to it. One method which wouldn't require a constitutional amendment would be to significantly increase the number of states, by splitting the existing six states into multiple parts, which in turn could significantly increase the size of the Senate and hence the House – but that is even less likely than a constitutional amendment is.

[0] an "Original State" means a state at the time of the Australian constitution's enactment. Australia currently has six states, all of which are Original States – like the US, the Australian constitution has a procedure to admit new states, but unlike the US, that procedure has thus far never been used

[1] the procedure for amending the Australian constitution is very different from that of the US – a national referendum, with both a majority nationwide, and a state-wide majority in a majority of states. What it has in common with the US constitution, is being very difficult to amend in practice – because most attempts to change the Australian constitution end up failing to pass the referendum