I am wondering why some communities are treated harshly by the Saviors and some like the Kingdom are not. I think we got answer in Go Getters when Simon tells Gregory that the group of Savoirs that were dealing with the Hilltop were too relaxed. My theory is that the only way Negan could have set up a system so quickly and so vast was to give autonomy to his "Generals" on how they collected. As long as they collect Negan didn't seem to micro manage. The Saviors dealing with the Kingdom (I think that the killed the group that Ben's father was in) seemed to compromise a solution where they didn't come to the Kingdom. The original Hilltop Saviors also did not come to the Hilltop but supplies were delivered to them. They only came with Simon. The Librarians thought they could fight back and were all killed by Simon. Oceanside fought back and all the men were killed. I think not only is Negan looking for supplies but is also on the look out for new Generals. Which is why he seems so obsessed with Rick. No one has ever challenged Negan like Rick has and Negan needs to know how . We get a hint that Negan is beyond the survival mode and is looking to create this brave new world in his image, hence wanting babies, and Rick is already more advanced that he has two children .