@ts1depot - I'm aware of how formerly active Sims behave when they become townies. This isn't that.
My version of Hylewood is still being developed as a non-rabbit hole world. This type of world takes quite a while to develop. The sims I am seeing this behavior from are the only two Sims who reside in that world. They live in the same house on the same lot and are always my 'active' household.
These sims are used for a variety of things related to world development. I play test my builds with them, have them upgrade whatever needs upgrading, plant and maintain gardens to build food stock for the town, create medicines, tools and pretty much anything else which is needed to get the town ready to be populated.
All objects for learning and entertainment are kept on their home lot. There are no parks, stores or any public buildings except the town's school for them to visit. The school is also set to 'No Visitors' but I have had a couple of 'world crasher sims' sneak in to use the objects there.
Being that there is literally nowhere to go, nothing to do (besides fishing) and no one to currently visit in Hylewood, I don't understand why under these conditions my sims wouldn't just go home even if they weren't programmed to do so (which I think they are).
Also, I'm not a cruel simmer, these Sims are not chained to their home lot. They do have a large number of friends thanks to WA and NRaas' traveler mod.