Sewer Rats

Hi. First time posting, I guess. I've been playing RTW for a while, and also a lot of RTR, as well, and I've noticed something about the AI. Whenever I take a city, there seems to be very little in the way of sewers. It seems the AI in the game does not build these things, so I'm stuck building sewers and the like just to get the population to a stable point.

I don't know if this has been mentioned yet, and I'm not sure if this happens in EB, but I was wondering if any of you guys encountered this problem, and if you knew how to fix it, or if it's hardcoded.

I mean, honestly. Does anyone really want their great conqueror shoveling feces for 2 years every time he takes a city?