Has anyone else noticed that, when playing a skirmish against the AI in a RTS game, they tend to 'give up' fairly easily?

For example, in C&C Generals, destroying the enemy command center causes the enemy attacks to steadily die out. Surely, they should've been programmed to rebuild?
Doesn't the command center control the construction of all buildings?
Not in Generals, you have builder units.
In all red alert/C&C games, if you destroy the Construction yard(s), the enemy will come with 1 more attack. The attack is basically all the men they get from selling there buildings.
I haven't played Generals. I assumed it was like the other games in the series. It's probably just something the programmers didn't think about putting in for the AI.
Not true, Derek[etc]. As long as the enemy has an offensive capability (i.e. barracks, war factory or something that can build units) they will continue to attack.

I reckon that the A.I cheats with resources on generals. I had the enemy totally cut off from any resources, and they were still launching big attacks and building scudstorms. They aren't the kind of thing you can build with the $20/s the GLA extra-cash building (black market) gets them.
Perhaps they sold really good guns in their black market? Also, the AI in the CnC games have always cheated when past the normal setting. This is the only way to give a tactical advantage on an even playing field beyond enhancing the AI to super levels.

With the AI set on its hardest mode, the AI normally has half an army before you have a barracks. This bothered me, but it was the only way I would be challenged by the AI.