The US results are strange. A lot fewer worry about healthcare and inequality/poverty than you would expect. In fact only Sweden worries less about the latter.
How many would you expect to worry? In a rich country with ample jobs and cheap food,I don't worry about it much either. I've seen poverty abroad, so maybe I just don't see what Americans call poverty as poverty.
You might have seem poverty abroad but there are plenty of countries on this list that worry more (like Germany) which much better working conditions for the vast majority of people with little income.