What criteria does BA consider when determining which particular country requires 400/800TPs or 600/1,500TPs for Silver/Gold? Presumably the amount of competition figures highly.

For example, although I understand most (if not all) of Europe requires the lower thresholds residents of Israel also enjoy the lower threshold while it's immediate neighbour, Egypt (where I work), has the higher threshold.

Given that my wife and I usually end up with around 1,000TPs per annum - although my first ever 1,500TP haul is still on for this year - we might otherwise be genuine long-term (as opposed to Eurocheat) Goldies; instead we normally both settle for Silver.