From that screenshot those Capitals don't look unusually close. From what I've seen most map scripts try to evenly spread starting locations from each other, but each Civ's Starting Bias can throw this off. If you have a map with relatively little jungle terrain, and 3 Civs that all have a "Jungle" starting bias then they could all start jammed up together around the same jungle-heavy part of the map. This is one of the reasons I like playing using the Communitas map script, as it tends to generate numerous pockets of jungle/forest/desert/mountains so that starting bias doesn't force Civs to start right next to each other. Even so, every so often I will still see two Capitals within 6 tiles of each other. It's rare, but it happens. I'd rather that then the alternative, though. The game is very boring to me if I have plenty of space around me to expand and settle cities. It's why I have a love/hate relationship with Polynesia. Their UA is a blessing and curse for me, because I know I can always run off into the ocean and mass-settle island cities right from the start. I always tend to over-expand whenever I play as them.