Watte & daub/cob is a very old construction material that had more than proven itself to humanity.
It insulates well in the summer heat, it keeps the heat in during cold winters and it is resilient to fire and termites. I would also presume it could survive hurricanse better, especially if built relatively flat.
I in the 21st century live inside a watter & daub building built around 130 years ago, so it wasn't abandoned in Hungary.
Why didn't Gold Rush style mining towns not use this technology, why did they use the more fragile lumber as material?
The international diversity that settled California during the 1849 Gold Rush did utilize wattle and daub, but not consistently. The key in "extensive" placer mining was the fact that limited local deposits kept everyone in motion as they moved to the next place ... and then the next. People built whatever was expedient and expected to abandon it shortly, so not a lot of effort was expended, at least initially.
That said, I have seen wattle and daub here and there. Keep in mind, however, that in the forests of Sierra, ample wood was available, and people tended to build what they knew. Much of the Eastern architectural traditions were based on wood or masonry, so it is not surprising to see communities established by Americans duplicating those styles.