There are a LOT of variables which can affect how Ai's economies develop; starting extra-abilities, government switching, buildings, morale, and a huge number of different values for many other things.
When i was designing X-Worlds, it mattered much to me that the financial side could be adapted to any races all the way from Minimal to Maxed out as compared to the player percentage (AKA, normal setting). I figured 110% to all would provide a reasonably challenging context; not SO!!
And here's why... the algorithms do adapt to many specific conditions as the game progresses. It could react to a nearby threat and even, suddenly full-spin around it's basic strategy towards Warmonging or better Research outputs in as fast as you could blink.
Lesson is that the mathematics of a booming economy has more to do with CURRENT ongoing conditions than it does with whatever financial edge percentages WERE determined upon game initialization.
I'd say that 90% of the time, the AIs are all extremely quick when it comes to modifying their "overall activities"; happy population (hint,hint) that pay taxes included, btw.
As a result, gameplay balance isn't (and never will be) the same... even when 150% financial pluses are applied to enemy settings, cuz in the short-term these AIs exploit any sort of situations to THEIR advantage. They'd even buy a soul if they could.