I'm pretty sure Hard AIs do not gain any income advantage -- they just seem to spend it more effectively than we do because they have no sense of foresight or self-preservation.
Human player: "I'm gonna need X soon, so I won't get Y right now," when nine times out of ten you could afford X anyway.
AI player: "I don't even care, I'm just gonna research all the things, spam all the ships, and get all the planets."
But what makes an AI player ultimately beatable is their predictability. They will always attack when you're not at a planet (so leave choke-point planets only when you have adequate defenses), and they will inevitably attack with combinations of ships that can be beaten with proper fleet synergy.
They do for sure. Just play the game for few minutes, then turn it off and check the difference in the planet income graph. You will see AI is getting 2,25x more income from planets than you do.
i teached my 2 friends to play Rebellion, they never played Sins before. They are however RTS veterans, they played lot of CnC and Supreme Commander in the past and while Sins is different, it is not that much different.
i played maybe one or 2 games with them against Normal. We did not even bother with Easy. I guess thats a difficulty for people, who never played RTS game before, or do not have anyone to explain things as they go (like they had me). After those 2 games, it was obvious the Normal was not a challenge anymore - i guess even them could beat multiple of Normals by themselves. So we simply had to move to Hard and the difference in difficultly is staggering.
After maybe 10-15 games we played, i think we won maybe half of them. The rest we had to restart as the AIs ganged up early game on one of us, he obviously had no chance due to AI superior numbers (thanks to income advantage every AI had about 2x more ships than him) and we could not really help him in time as we were too far away. In such situation the rest of us can technically kill one AI off, while they concentrate on him and try to win basically "last man standing" style. But that is not an option, if play together, we want to see the end of the game together.
Anyway I think we are getting better now and eventually we find a way to win consistently. But i played the game since last March and they are smart guys with experience playing RTS games, so they can learn pretty fast. I can however see not everyone is like them and can really have serious issue with Hard difficulty, to the point, where the frustration stops him from playing the game further.