Interesting, I never paid attention to that. I would guess the number of singles/couples earning $40k/$80k total per year or less and own enough stock to get material dividend income must be miniscule.
Lots of retired affluent people fall into that category. A $4M portfolio would throw off $80K in annual dividends assuming an average 2% dividend rate.
A retired couple with $4M net worth excluding home value is 97th percentile. $1M is 90th percentile.
And they surely would have a significant proportion of assets in bonds yielding a couple percent rather than stocks, so earning tens of thousands in only dividend income is probably super rare.