I believe God blesses a nation to be a blessing to other nations. I do not believe it means favouritism, just as much as I do not believe those chosen by God to prophecy/warn others are especially favoured or superior, but rather God works through whom He wishes to reach others.

It's always been that way. Only God knows why. All people are equal in importance to Him, or He would not have died such a cruel death on a cross for each human being (no exception)....so I hardly see how anybody could possibly claim "unfairness". It is actually a great responsibility when God calls a person/nation to be a help to others. I would not wish to answer to Him if such a blessing had been bestown to me and I had misued/abused it.