If many of those people aren’t earning to give, then either fewer EAs are earning to give than is generally assumed, or the EA survey is not a representative sample of the EA population.
Alternatively, we may question the antecedent of that conditional, and either downgrade our confidence in our ability to infer whether someone is earning to give from information about how much they give, or lower the threshold for inferring that a person who fails to give at least that much is likely not earning to give.
If many of those people aren’t earning to give, then either fewer EAs are earning to give than is generally assumed, or the EA survey is not a representative sample of the EA population.
Alternatively, we may question the antecedent of that conditional, and either downgrade our confidence in our ability to infer whether someone is earning to give from information about how much they give, or lower the threshold for inferring that a person who fails to give at least that much is likely not earning to give.