Not to mention their inability to use the stairs if someone else is on them and the fact that they can't step over the newspaper to leave the house

Only fixed stairs and only because it's one whole single object. Switch to modular where each step is separate and multiple sims can use those.

And if you like the look of the fixed stairs, someone made some nice covers for the modular ones to look like them! (I haven't a link, though.)

@Orphalesion Wood lice. But, the point about being able to change the environment, move things, that's a really good one. I'll have to think about that. That being said, if we create one sim in the family who is obsessed with cooking and one who is obsessed with cleaning, the breakfast might get made and the dishes might get done, which is rather like the division of labor in eusocial insect colonies, I guess.

In my mind, all these "stupid" behaviors (hot tub, stairs, newspaper, treadmill, etc) just reveal more about how the sims "think". Hypothetically, over time, I should be able to "fix" these things to create a more and more autonomous environment. That's the idea anyway. Of course, it's just play, so it's up to me what I think is fixing and what I think is cheating-so-much-it's-not-fun-anymore.

So, for instance, I grabbed those trees that @Charity posted earlier in the thread and am LOVING those. They drop edible fruit every 3 days and the sims will eat them autonomously. To me, in a camping or farming environment or a community garden, that makes total sense. Of course, the sims would eat their fruit! (Cloned on the pizza slice they eat when the landlord orders one for the apartments.)

Also, during all this past week, I'm still setting the sims up and playing without aging, meaning I have no problem with letting my sims grow into independence as they learn and form stronger relationships over time. I'm finding a huge advantage, for instance, in letting children stay children for a lot longer, especially in my multi-family apartment environment where they have strong relationships with a number of adults whether active or not at the moment.

As an example, maybe that's why I saw this unexpected autonomy the other day - in the apartment environment where the four families all have interconnections and are all playable, I had a child sim who was unrelated to the active family and not living in their household jump in the communally used truck at the last minute to stow away on a drive to the community garden when the unrelated active adults drove away. I had no idea that was even possible. Sure enough when we arrived at the community lot, he was there with the adults, no apparent glitches, and he appeared to leave with them much later, but when we arrived back at the home lot, he was not in the truck. However, in just a moment, he came walking back. (After all, it is just across the street - ) Seriously, how is that even possible? Anyone else seen autonomous stowaways?! Of course it feels very twilight zone to me, but it's more likely a deeply buried, unlikely, action that can be seen over time when relationships are strong or something like that. IOW, it may be that greater autonomy is built in, but buried.

Anyway, it's been a fun way to spend my holiday at home when it's much too cold to go out.

EDITED to UPDATE: Well, with just a couple of mods and the advantages of a community lot, this turned out to be surprisingly easy. I have 4 elders in Desiderata which I haven't played otherwise at all. One's a clone I made for another neighborhood, the two Goodies, and Dora Ottomas. They decided to get together and live the Home Free life in their later years. Iow, they are camping. (Originally, I was playing them more like a homeless challenge, but it led to lots more community lot use than I usually do - hence the discovery.) At home, they sleep in 2 tents, have Dr Pixel's outhouse, lots of Sunni and Frac's autonomously edible fruit trees, one of Sophie-David's storybooks, and a fire. That's it. They are not stupid enough to camp in snow so they live in a warm climate. They walk to community lots for showers, cook-offs, etc. They've had minimal help surviving (they won't walk to lots on their own), but they do a lot of other things on their own. They've taken to tent "swapping," but who can blame them at their age and they *are* all very close friends. They eat autonomously, both from the fruit trees and on community lots. They love that storybook and will sit around reading from it for hours, so they received membership in the Desirable Discourse Club. This turned out to be very lucky. Once they walk to DD, they can, apparently, live there indefinitely, or, at least, they appear in no danger of running low on needs. I gave them a sleep-on-community-lots mod (to me this is only sensible and entirely fair). On their own, they even order drinks and watch the cooking channel as well as take showers and grill hot dogs. I assume eventually they would run out of money for those things. For now, though, they've figured out the goodies at DD and can hang out there quite safely. I think it's open 24/7 and the few other members don't seem to mind.

If I were doing this on purpose - I really didn't start them for this - I would have them live full lives and achieve all their aspirations before heading off on this adventure so they would not have any regrets that make them burst into tears now and then.