The algorithm is a little difficult to understand but people can certainly be assured that it provides the right result. The electoral officer issues an Excel file with the correction coefficients and people can check that the result is correct. The proportionality is easy to calculate; everyone can do it with Excel at home, and it gives the right result. So people have a degree of confidence.
In the canton of Geneva, it was proposed but not accepted. The argument from the politicians was that, in that canton, there was no electoral threshold and if they were to proceed, they would need an electoral threshold. They had never had one and they did not want one. An electoral threshold would mean that some parties would fall below the threshold.
This has been studied in a number of places. Everyone has the same concern. It's not super-complicated but it comes as a bit of a shock. Votes are not equal at the moment. So you are making them equal again. If you understand that, everything is fine. The algorithm is not very long—20 to 30 lines—but it is a bit mysterious, which is where the psychological barrier lies. When you talk about compensating with a second category of members, it is more intuitive. You add members in order to achieve balance. The advantage is that you can keep the geography much more precisely. In the case of Canada, that is more of an advantage.
It has been debated in the United States, but not very publicly. In England and in the Faroe Islands, it was examined a little. Often, it is in countries that already have a regional proportional system. They have a problem because there are never fewer than three members in an electoral district. That creates distortions because the small parties in three… The psychological distance is less because those places already have a proportional system. The others see no proportionality because the electoral thresholds are too high.