That doesn't track entirely because the behaviors they're talking about are wearing masks and staying 6ft away from people. Both behaviors cost nothing.
Even in relatively spaced-out areas, this is true. If you go to Central Park, you'll find that the density of people on an average day is far higher at (say) Harlem Meer than it is further south. There are simply more people who are sharing the same recreation space that is within X miles of the place they are living.
Central Park is actually a silly example, because it's far better than most other parts of New York. Go to Fort Washington Park on an average sunny weekend, and the density of people is dramatically higher than Riverside Park, further south. And that's just recreation...poorer people have less time for that than rich people do. Go to Flushing, and people are cheek-to-jowl at pretty much all times, even though there's a big empty park right next door.
At least in the US, the poor have significantly more leisure time than the rich.
https://www.theatlantic.com/business/archive/2016/09/the-fre...
Even if the working rich work more hours than the working poor, the situation might be reversed when one includes commute time from and to, and between jobs.
Though I will grant you that wearing a mask does cost less nothing*.
This is not true for the latter. Many people, especially some with little means, have little practical ability to maintain social distance.