When Obi Wan comes in to land on Kamino, you can see another “oil rig” in the background.

Presumably there are more than two, but can’t be seen in the rain and general murk. (IIRC, we see a lot more of Kamino in the TCW series.) That Obi Wan lands on the one where the head guy happens to be, and Jango has his swinging bachelor pad is a coinkydink.

There are other Kaminoans, you just have to look harder.

As to why there seems to be so few of them around the facility, I presume Obi Wan showed up on a weekend.

I still chuckle at the soup ladle/ice cream scoop chairs they sit in. 😉

They don’t look like they would be comfortable for either species to sit in very long.