19 And the priest shall offer the sin offering, and make an atonement for him that is to be cleansed from his uncleanness; and afterward he shall kill the burnt offering:
20 And the priest shall offer the burnt offering and the meat offering upon the altar: and the priest shall make an atonement for him, and he shall be clean.
21 And if he be poor, and cannot get so much; then he shall take one lamb for a trespass offering to be waved, to make an atonement for him, and one tenth deal of fine flour mingled with oil for a meat offering, and a log of oil;
22 And two turtledoves, or two young pigeons, such as he is able to get; and the one shall be a sin offering, and the other a burnt offering.
We have seen before how the conditions of an offering could be adjusted according to the wealth of the subject. Other things could not be, where the same offering required of rich and poor. The fact that variance was allowed in the offering of the healed leper speaks to the human condition where misfortune befalls us all.
Leprosy was not only an affliction of the poor and the old, but even of the young and the rich. It could even befall a high ranking military leader, such as Naaman. Righteous people could have leprosy, and wicked people could also.
It is woven into our nature to expect good for good, and bad for bad. That expectation is due to our appropriate understanding of justice. And to some extent, there is some truth to it. In general, the righteous avoid a great deal of affliction and stress because of their clean and honest living, while the wicked bring natural negative consequences by their dirty and offensive behavior. But in this fallen world, none of this is absolute. The righteous and the clean-living will still get cancer, still have to bury their child, still be at the mercy of the wicked. So, knowing that virtue alone will not protect us, we often seek further assurances in wealth. And with it many ailments of life may be staved off, but it is still not absolute. Even the rich will have an earthquake destroy their home, develop a crippling disease, or lose much of their estate in a messy divorce.
So, too, rich and poor alike could have leprosy, and their offering requirements for cleanliness would reflect that.

