I really wish I was into Betta's when I was in thailand 6 months ago, I would've tried to go search for this stuff. But if I take a step back and look at nature as a whole, plenty of different fish end up in places that isn't preferable but they survive. Especially with monsoon seasons and droughts. Water goes up, water goes down, the area disappears and pockets, pools, puddles are formed. This is also as far as I understand, the reason bettas jump at night. To change location when this happens.
I doubt any fish could survive years in a natural body of water that is a foot square or less, simply because it's incredibly hot in Thailand, so that tiny amount of water would dry up in 2 days and you'd have a baked fish. Secondly, a bright moving fish, in a foot of water, would be easy prey for birds, wild dogs and any other predator.