Earlier quoted context omitted.
One can just look at objective data: https://www.oecdbetterlifeindex.org/ People that say US is a third world country are mostly illinformed, my guess is due to political affiliation as you said, but also the city dynamics, arm chair media consumption (NYT exclusively reports vocal minority issues day in day out) and uninformed about what actual third-world countries are like.
Looking at the data, the sample size is quite pathetic. https://www.oecdbetterlifeindex.org/bli/ The amount of responses is skewed largely to 2-3 countries and the self-report guide is unreliable. On top of that, by their own admission here: https://read.oecd-ilibrary.org/economics/how-s-life_97892641... their empirical data does not account for factors like wealth distribution, and a lot of the subjective indicators…
Well the “US is a third world country” take is based on no evidence whatsoever and defies all common sense, experience, etc, so I guess I’ll take the significant but imperfect evidence.