I've been playing a few games lately and noticed the economy scale doesn't work, maybe broken in a recent patch? Playing a game with a friend and having the A.I. set to 0.1 or 0.25 and us on 1.5 and it doesn't seem to make a difference. It has done in the past. We have tried it with both of us setting the scale in the same way also.
I'm only played against AI in previous version and it's worked just fine. E.g for us economic multiplier give resource advantage as excepted. In 58772 I only played against AI alone and multiplier work just fine.
It didn't work at all for me and a friend. We were doing a free for all with one A.I. and it was pretty hard. using A.I. scale 0.1 and us on 1.5. Tried 0.25 too. They didn't seem like they were handicapped at all and I have used it before and it made a massive difference.
When I am testing I often set the AI to 0 and myself to 500+. Works just fine, even in the most recent patch.