earthen floor regulations roof

Question about why no earthen floor and why no living roof.

They talk about the great value of earthen floor and how cheap it is. Then he says we want to make a earthen floor at some point for one of "our houses" (how many houses is he going to own? :p I suppose hes starting with his house but then doing this with other peoples houses too? ) "but its not right here" Why not? If there is nothing but advantages for earthen floor, why use concrete instead?

Also he talked about the benefits of having plants growing on roof for insulation and cooling in the summer (as well as being able to have that space for enjoying yourself if you have a way up) Then he said he'd love to have that but local regulations didn't allow it. Why would their be such rules/laws? What are the disadvantages to the community that they would make it illegal to have a living roof?

It would be nice if such details were mentioned in the show BTW.

Also, if no living roof, will he be using any solar panels on that metal roof?