alt Hacker News> [...] they cannot control for the willingness to respond to polls at all.
I believe this is not true, because at least ESS (European Social Survey) corrects for non-response, although how exactly is beyond my understanding of survey analysis. Each country reports the response rate as well. See [^1] section 3. Although ESS is much larger survey than simple opinion poll, there are political affiliation questions too (`^prtv.*$` variables).
[^1]: https://www.europeansocialsurvey.org/sites/default/files/202...
Appeal to authority here. If you know statistics you know the truth is basically impossible to model. The great lie of statistics is you are measuring associations that are true in your dataset and you are making assumptions that this dataset will be more or less representative of the population and perhaps sampling 10 of 1000 will be sufficient depth to appreciate this true result.
Sometimes this works out alright. But sometimes not. Too many factors in the universe to model. Never enough power to look at all them even if you knew what they all were. It works well when a few dominant factors are present but when its a million latent factors with technically every pairwise interacting relationship present in some degree, good luck.