Storing vehicles is a social problem not an individual one, given that by their nature people tend to use them to commute, go shopping etc.. (If you live in some crazy jurisdiction that has decided to allocate lots of public space to car storage and not bike storage, then you have a problem, but, uh, don't do that)

The issue with bicycles in public spaces is that they get stolen all the time, even the shitty ones. Folding ones neatly avoid that since you can rather easily store them somewhere safe wherever you go.

Honest Q: where though? If storing outside on a bike rack isn't an option, where can the folding bikes be reasonably stored while out and about? If I go to the store, for example, I see no option but to lug the bike around with me the entire time. At work, sure, I could stash it in the office during the work day, but outside of that I'm not sure storage really works.

I would say home/the office is already pretty big. You're right, you probably won't store your bike in the shop, but if you're shopping with a bike, you probably won't stay there for a long time anyway so the risk is quite lower. For what it's worth, I've seen people put them in some corner at the gym for instance, so it's sometimes possible.

I'm not saying it's perfect, but I certainly see the appeal for commuters, especially as a last mile option. You usually can't go with a full bike in public transports during rush hour anyway, so the usual alternative is to have one bike at each end, where they are outside all the time.

At my local store(s) there's plenty of parking space, but no bike rack or a railing to lock a bike. At the gym, there's a bike rack right in front but no parking space. For my commutes accessible by bike, a folding bike offers no current advantages. The option of a bike that's easier to take on the subway is certainly appealing though.

My bike is actual not theoretical.

Storing it is very much my practical problem.

The solutions are orthogonal to the presence or absence of parking lots, quays, and hangers in my community.

For me, folding it up and putting it in a closet seems simpler than changing civilization. YMMV.

I actually did emigrate for the sake of a better life that includes a much better bicycle culture, FWIW :).

Better bicycling in the public sphere is among the benefits of my relocation.

The folding bike improves the situation in my domestic life.

In general a bike is a both-and to an automobile not an either-or.

Each is a tool that is better for some jobs and worse for others. As tools neither is moral or immoral, virtuous or evil, inherently right or wrong.

I'd argue that a tool is inherently immoral to the extent that it tends to impose negative externalities on others.

Now do cars.

I leave my car outside because rain doesn't effect it's powertrain lubricants.

It has integrated locks and unlikely to be stolen. It can't be picked up and thrown in the back of a van.

Or just ridden off.

I come out and the seat isn't wet and the chain isn't rusty.

Everything is dry and ready to go.

It's a funny list considering bikes were described as a compromise with floor space. As it's possible to park 10 bikes for one car.

As for the rest, I lube my chains rarely and they are rusty on extreme occasions only and stand in the rain often. Belt drives also require no lube at all. A bike can be dried up in 5 seconds or you can use a seat cover which costs around 50 cents on average unless you get it for free. You take it off and the seat is dry and ready to go.

And you don't have to drive around three blocks for 10 minutes looking for a parking space. Or longer if you don't find it and drive home and ride a bike instead. So cars are a compromise with mental health and bikes are a breeze. I haven't had to worry about anything or make any compromise with them in so 12 years I've been riding daily. Because even a rusty chain can be replaced for 10-20$. They are basically worry free and almost maintenance free. To call them a compromise is an insult to common sense.

I don’t need to park ten bikes because I only have one and it folds up and fits in a closet or can roll behind me somewhat like a carry-on suitcase.

I don’t disagree with your experience regarding maintenance. Mine has been with a bike in Florida rain, where the streets run yellow with pine pollen in spring, and where the fog is of the Pacific’s salt air.

With my folding bike, I just find a place to park the car and peddle the last mile or don’t and just walk. A car doesn’t require me to park close.

Car or bike or foot, I tend to maintain my chill about the same frequency. I stopped competing for parking a few years ago. Cannabis helped. YMMV, but it helped on the internet too.

If you only have one then I especially don't understand what kind of compromise you need to make in relation to the floor space. It's the most efficient transit vehicle with regard to space, folded or not.

Your use case is ok, I have a friend that does something similar when his wife takes their car for the day. But even without a folding bike it would be trivial to put a rack for the bike on the back of the car.

Take care.