So they're building houses out of sandbags? What if the plastic bag breaks? Why don't they coat the whole structure in something a bit more resistant to a kid with scissors?
Why don't you RTFA? In which you're questions are answered.
> For permanent structures, the synthetic bags are plastered over to provide an erosion resisting layer, or they can be removed when the stabilized earthen filler is cured.
Adobe structures are extremely durable, and account for some of the oldest existing buildings in the world.
Adobe buildings are known to be particularly susceptible to earthquake damage, a problem that was solved for super adobe.