In my part of the US, a temporary structure does not require a permit or zoning allowance, while a permanent structure does. When we build sheds to meet the "temporary" definition, they are built on top of cinderblocks and not a poured concrete foundation. In this case, the author built his shed directly on top of his patio, so I am curious whether this would be considered a permanent or temporary installation.
I think this would still be temporary in my area because you can pick it up and put it on a flatbread trailer. The wiring might change that.
I think there are still lots of rules to follow.
Bonus points for the temporary trailer.
The question is how many flatbreads you need for building one.
This is from California which is, uh, not known for a light regulatory touch in things like permits or zoning.
In Santa Cruz it is illegal to insulate your garage, lest it become housing.
CA has been lightening up about ADUs, it's typically not hard to put one in. There were a few legal changes in 2020, allowing larger sizes, less planning oversight, less parking requirements, utility hookups can be shared with the primary building.
The permits are pretty easy to get.
I live in SF bay area and I can build a accessory structure of 150SF or smaller without a permit.
Don't assume we're all girdled by (presumably) US building codes.