‘For I do not say this that others may be eased and you distressed, but by equality: your abundance being a supply at this present time for their want, that their abundance also may become a supply for your want, that there may be equality.'
Let them recognise that the purpose behind all this is not to make life easy for others as a result of distress brought on them (something which Roman and local taxes did do), but for both of them to share equally in God's basic provision. At this present time their abundance could help meet the needs of those in dire want. At another time their poverty might be met by receiving from someone else's abundance. The purpose was that all might be equally supplied by each other with their basic needs.
Note that the ‘equality' does not indicate that all should have the same. It is speaking of equality of treatment. That each, when in great need, should be assisted by the other.
Some argue that Paul could not possibly have seen a time when the Jerusalem church would be in a position to reciprocate in physical assistance, and therefore argue that the reciprocation is in spiritual abundance. But 2 Corinthians 8:15 is against that idea. And he could well cite Old Testament prophecy which demonstrated that a turn in fortunes could easily come for Jerusalem.
However, we need not see Paul as prophesying that it would be, only as stating a principle. His idea was of all churches in the world being concerned for each others basic needs. The African churches of today have thereby a Scriptural right to enquire as to why we leave them to starve. But they are probably too spiritual to ask, and we are not spiritual enough to notice.