Exposure to mold is also likely to be correlated with socioeconomic status, especially in more humid parts of the country. Think what kind of people are most likely to live in rundown houses (or even basements!) barely above the water table, without a functioning HVAC unit.
Mold is the kind of problem that is at most a nuisance for people who have the means to do something about it, but seemingly unsolvable for people who actually need a solution.
This! One of the best solutions to prevent mold is to improve energy efficiency. There are an increasing number of grant programs and Housing improvement initiatives available, but still those improvements are out of reach for a lot of people. We live in the Southeast US which is incredibly humid and so many houses have issues.
Mold is the kind of problem that is at most a nuisance for people who have the means to do something about it, but seemingly unsolvable for people who actually need a solution.