Re: poorer - my partner needed the car on the day I had scheduled a jab, so I had to walk/train. The appointment, as a whole, cost
an entire morning. I can work around that, but the practical issues are obvious.
A friend's anecdotal evidence was that skepticism was U-shaped as a function of age - there were older black people much more likely to have close experience of mistreatment. For reference I'm not in the US and some still bring up tuskegee, but also more typical things that do apply locally - "oh some skinheads beat you up? What a shame. Might be nasty if you made an issue of it" type stuff. Younger generations have had less mistreatment - not none, but less - and, like everyone else, are divided between pragmatic decision makers and conspiracy theorists.
Of course, if you're from certain regions of Pakistan, there is much more recent evidence of vaccines specifically being misused, and was also discussed recently on HN (as a point of pedantry, the people in question did get real vaccines. Still pretty awful). I don't believe this has had as much impact as certain sections of the media with a fetish for diaspora narratives and a poor grasp of geography would like.