Cannot answer your historical question, but maybe I noticed something relevant today.
I went out this morning with a couple of dozen Japanese to do a dragon dance (Ryūjin) around the local village. Exactly like this one[1] from 8 years ago.
80% of the dancers were wearing tabi. I figured out why. Upon re-entering the community centre from where festivities are organised, tabi-wearers could just wipe their feet and enter. The rest of us had to hold that dragon while simultaneously removing shoes and stacking them.
Socially, tabi are the only acceptable in-and-out shoes/socks I have seen here.
After a shortage of leather, "Manufacturers switched to making tabis from cotton and other fabrics. And here is where the shoe started turning into a sock."
Shojiro [...] "developed a new kind of tabi made of thick cotton and a rubber sole. They called this a jika-tabi (地下足袋) which loosely translates to “tabis that touch the ground”. This married their expertise in fabric tabis and their experiments with a material that was relatively new to Japan. And turned the sock turned back into a shoe."
So basically the most common variation in different times changed depending on available materials and these days cotton tabis are used only as part of traditional dresses.
>Don't know of any other country that doesn't use shoes.
Not only "shoes", they usually need to be conformant to local safety norms (EN ISO 20345 in Eu) that include a "hard point" (resistant to 200 joule or 20 kg falling from 1 meter height) and - usually - an anti-perforation layer underneath (those used in construction, at least here in Italy are either S1P or S3 type).
Unrelated: Roofers in Australia started wearing an early tennis shoe that was cotton canvas with a sole that emulated a rubber tire. It became so popular they made a steel toed version. Only steel toed tennis shoe I know of. https://volley.com.au/products/safety-canvas-black-grey?vari...
The regular ones are fantastic by the way. Very comfortable, insanely flexible and grippy. But they do tend to fall apart quickly. In AU they're very cheap, but more expensive for us.
Yeah, if we say the three stages are 1) leather (shoe), 2) cotton (sock), 3) cotton + rubber (shoe), then (1) is extinct but (2) and (3) both exist today.
It sounds to me like several designs emerged at different stages from the same root idea, rather than a linear transition from one thing to the other.