This is… a mathematically correct but practically useless way to compare migration flows. Using this approach, Singaporeans are more likely to move to China than Chinese to move to Singapore. Mathematically true, and tells us much about the relative sizes of these two countries, but very, very little about relative attractiveness as a place of living.

>Using this approach, Singaporeans are more likely to move to China than Chinese to move to Singapore.

Using the Our World in Data figures, a Singapore-born person is about four times more likely to move to China than a China-born person is to move to Singapore.

That does not seem like an unreasonable ratio, given that a) Chinese are not nearly as free, whether economically or politically, to emigrate, b) those Chinese who have the money and connections to leave are likely going to be in the large cities that offer good living standards, and c) China is going to have, from sheer size, aspects that will appeal to Singaporeans regardless of per-capita economic disparity. Put another way, if Chinese were as free to move around the world as Singaporeans, there would surely be many more China-born people in Singapore ... perhaps four times as the current 530K.

By contrast, the US and Spain are fairly comparable in terms of their citizens' freedom to move about, so that factor can be eliminated from the comparison.

Voting systems in Europe differ by country, but for example here in Switzerland I just get my ballot in the mail, fill it in and send it back to get counted.

And of course Swiss Post just processes this as a regular piece of mail, routing it to the address written on the envelope, without any weird cross-tabulation against voter registers or barcodes…

Some years ago a postman in Spain was caught with a sack in his home with 3000 votes that never were delivered to their destiny. This happened many months after the election. Last year in December some thieves broke into a small village post office and stole the money and the sack with 124 mail votes that were found later partially burnt. The few voters involved were allowed to re-send his vote before the elections and an organization of 12 people were detained later for this an other assaults to post offices before the local elections.

So yes, mail voting has a few issues still, not a lot, but is not impossible to break. If every worker in the post office is from one party and nobody in that party votes by mail, bribing and corrupting the system is doable, and even easy; specially if your work depends on it.

If you do this in small populations or at scale you could easily remove enough votes from the system until winning the place by one single vote. If you are malignant enough you could even blame later millions of "lazy" people for not voting and laugh about it.

Mail voting depends on trusting what your postman is not a plant.